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AP State Syllabus AP Board 9th Class English Textbook Solutions Chapter 1B The Duck and the Kangaroo Textbook Questions and Answers.

AP State Syllabus 9th Class English Solutions Chapter 1B The Duck and the Kangaroo

9th Class English Chapter 1B The Duck and the Kangaroo Textbook Questions and Answers

I. Answer the following questions.

Question 1.
Why did the Duck get bored in life? What did it want to do?
Answer:
The Duck lived in a pond. It cannot hop like a Kangaroo and go round the world. When the Duck saw the Kangaroo going round the places, it felt bored. It wanted to tour places. Limiting to the pond made the Duck unhappy.

Question 2.
What problem did the Kangaroo find with the Duck? How was it solved?
Answer:
The Kangaroo was willing to take the Duck to new places. But it objected to the wet cold feet of the Duck. The Kangaroo said that would make him ill. But the Duck had a solution. It got socks, a coat, and cigars ready to save them from cold.

Question 3.
Who was happy in the end? Why?
Answer:
Both the Kangaroo and the Duck were happy in the end. The Duck was happier as its desire to see places was fulfilled. The Kangaroo too was happy as it could help his friend.

Question 4.
What is the underlying message in the poem?
Answer:
The poem is basically humorous. But it has valuable messages too ! Desire to see new places is a natural way to better oneself. Seeking others’ help promotes cooperative living. Foreseeing the problems and providing solutions is a good lesson.

II. Read the above poem once again and choreograph it as described here under.

Choreography

Choreography is the art of designing sequences of movements or actions for a script or a poem with a voice or a song in background.
Do you know how to process choreography?
Here is the process.
Think of the following.

1. How do we begin the poem?
(Sing the poem three or four times to register the tune and rhythm.)

2. What are the characters in the poem?
(The Duck and the Kangaroo)

3. What is the theme of the poem?
(Wish of the Duck to go round the world)

4. What is the theme of each stanza? (sub themes)

Stanza	Theme
1. First	Wish of the Duck to hop and go round the world
2. Second	Requesting the Kangaroo to take her for a ride
3. Third	Conditional acceptance of the Kangaroo
4. Fourth	Assurance of comfort from the Duck’s side
5. Fifth	Fulfilment of desire

5. Convert the themes into incidents and performable actions.

6. What are the actions involved in the poem?

• Boredom with present life (feelings of boredom, pain)
• Desire to go round the world (miming)
• Wearing socks and smoking cigarettes (joy)
• Displeasure due to wet and cold feet (gestures)
• Sitting on Kangaroo at the end of the tail (miming)
• Joy (facial expression and gestures)

7. Who are the characters involved?
(The Duck, the Kangaroo and other creatures in the pond like frogs, fish, etc.)

8. Where does the incident take place (location)?
(By the side of the pond)

9. Presentation of the choreography on the stage:

• The chorus team sings the poem
• The characters perform their actions
• The action of the Duck and the Kangaroo- expressing boredom, wish, discomfort, joy, etc.
• The actions related to miming, facial expressions and gestures
• Actions related to hopping, sitting, walking, jumping, etc.

The Duck and the Kangaroo Summary in English

‘The Duck and the Kangaroo’ is a poem with a touch of humour. It was the creation of a British poet called Edward Lear. The Duck says that it is bored with its life in the pond.
It wants the Kangaroo to carry it around the world. The Kangaroo says that the Duck’s cold and wet feet will make him ill. The Duck says it has a solution to that problem. It will wear socks. It will also have a coat and smoke. Then the Kangaroo asks the Duck to sit on his tail. The Kangaroo hops around the world thrice with the Duck sitting on his tail. The
poet leaves the question – as to who is so happy? – to the reader!

The Duck and the Kangaroo Glossary

Good gracious! (phr) : an exclamation expressing surprise and emphasis

nasty (adj) : unpleasant

long (v) : have a strong desire

the Dee and the Jelly Bo Lee (n) : wonderful places imagined by the poet

reflection (n) : thinking, consideration

roo-matiz (n) : rheumatism (n) – a disease that makes joints and muscles painful; arthritis

worsted socks : woollen socks

cloak (n) : coat

pale (adj) : low, dull

steady (adj) : remaining in the same position

AP State Syllabus AP Board 9th Class Physical Science Solutions Chapter 5 What is inside the Atom? Textbook Questions and Answers.

AP State Syllabus 9th Class Physical Science Solutions 5th Lesson What is inside the Atom?

9th Class Physical Science 5th Lesson What is inside the Atom? Textbook Questions and Answers

Improve Your Learning

Question 1.
What are the three subatomic particles? (AS 1)
Answer:
The three sub-atomic particles are electrons, protons, and neutrons.

Question 2.
Compare the subatomic particles electron, proton, and neutron. (AS 1)
Answer:

Question 3.
What are the limitations of J.J. Thomson’s model of the atom? (AS 1)
Answer:
The main limitation of J.J. Thomson’s model of atom was that he is unable to explain, how the positively charged particles are shielded from negatively charged particles without getting neutralized.

Question 4.
What were the three major observations Rutherford made in the gold foil experiment? (AS 1)
Answer:
The three major observations Rutherford made in the gold foil experiment were

1. Most of the space inside the atom is empty.
2. All the positive charge must be concentrated in a very small space within the atom called nucleus.
3. The size of the nucleus is very small as compared to the size of the atom.

Question 5.
Sketch Rutherford’s atomic model. Why is Rutherford’s model of the atom called the planetary model? (AS 5)
Answer:

Rutherford’s model is called planetary model because the motion of the electrons around the nucleus resembles the motion of the planets around the sun.

Question 6.
Put tick (✓) against correct choice and cross (✗) against wrong choice: (AS 1)
i) In Rutherford’s gold foil experiment, majority of alpha particles passed directly through the gold foil. This observation leads to which conclusions?
a) The positively charged region of the atom is very small. (✗)
b) The atom must consist of empty space. (✓)
c) The alpha particles makes a direct hit on the positively charged region of the atom. (✗)
d) The positively charged region of the atom is very dense. (✗)

ii) In Rutherford’s gold foil experiment, occasionally the alpha particles veered from a straight line path. This observation leads to which conclusion?
a) The positively charged region of the atom is very small. (✗)
b) The majority of the space in the atom is empty. (✗)
c) The alpha particle makes a direct hit on the positively charged region of the atom. (✗)
d) The positively charged region of the atom is very dense. (✓)

Question 7.
Which one of the following is the correct electronic configuration of sodium? (AS 1)
a) 2, 8
b) 8, 2, 1
c) 2, 1, 8
d) 2, 8, 1
Answer:
d) 2, 8, 1

Question 8.
Give the main postulates of Bohr’s model of an atom. (AS 1)
Answer:
The main postulates of Bohr’s model of atom are

1. Only certain special, discrete orbits of electrons are allowed inside the atom. These orbits or shells are called energy levels.
2. While revolving in these discrete orbits the electrons do not radiate energy and this helps that the electrons do not crash into the nucleus.
3. These orbits or shells are represented by the letters K, L, M, N, ……… or the numbers n = 1, 2, 3, …………

Question 9.
Compare all the proposed models of an atom given in this chapter. (AS 1)
Answer:
In this chapter, four atomic models were discussed. The main postulates of those models are

1. Dalton’s proposal :
a) Atoms are indivisible.
b) Atoms of an element are all identical to each other and different from the atoms of other elements.

2. Thomson’s proposal:
a) An atom is considered to be a sphere of uniform positive charge and electrons are embedded into it.
b) The total mass of the atom is considered to be uniformly distributed throughout the atom.

3. Rutherford’s proposal:
a) All the positively charged material in an atom formed a small dense centre, called the nucleus of the atom.
b) Negatively charged electrons revolve around the nucleus in well defined orbits.
c) Size of the nucleus is very small as compared to the size of the atom.

4. Neils Bohr’s proposal :
a) Electrons are revolving around the nucleus in special, discrete orbits called en¬ergy levels or shells.
b) While revolving in these discrete orbits the electron do not radiate energy and this helps that the electrons do not crash into the nucleus.
c) These orbits or shells are represented by the letters K, L, M, N,…. or the numbers n = 1, 2, 3,

Question 1o.
Define valency by taking examples of nitrogen and boron. (AS 1)
Answer:
Valency: The number of electrons present in outer most orbit of an atom is called its valency. Valency of Nitrogen :
a) Atomic number of nitrogen is 7.
b) The distribution of electrons is 2, 5.
c) The outer most orbit has 5 electrons.
d) Hence its valency should be 5. But it is easier to nitrogen to gain 3 electrons than to loose 5 electrons for becoming octet.
e) Hence the valency of nitrogen is ‘3’.

Valency of Boron :
a) Atomic number of boron is 5.
b) The distribution of electrons is 2, 3.
c) The outer most orbit has 3 electrons.
d) Hence the valency of boron is 3.

Question 11.
State the valencies of the following elements : magnesium and sodium. (AS 1)
Answer:
Magnesium :
a) Atomic number of magnesium is 12.
b) Distribution of electrons is 2, 8, 2.
c) Hence the valency is 2.

Sodium :
a) Atomic number of sodium is 11.
b) Distribution of electrons is 2, 8, 1.
c) Hence the valency is 1.

Question 12.
If Z = 5, what would be the valency of the element? (AS 2)
Answer:
1) If Z = 5, the distribution of electrons is 2, 3.
2) Hence the valency is ‘3’.

Question 13.
Write the atomic number and the symbol of an element which has mass number 32 and the number of neutrons 16 in the nucleus. (AS 1)
Answer:
Mass number (A) = 32 ; Number of neutrons (N) = 16
Number of protons (Z) = A- N = 32-16 = 16
∴ Atomic number =16
The element is sulphur.
The symbol of sulphur is S’.

Question 14.
Cl- has completely filled K and L shells. Explain. (AS 1)
Answer:
Atomic number of Cl is 17, but Cl^– has one more electron when compared with Cl atom. Distribution of electrons in Cl^– is

K	L	M
2	8	8

K shell can accommodate 2 electrons and L shell cab accommodate 8 electrons accord¬ing to the formula 2n2.
Hence the K and L shells are completely filled.

Question 15.
What is the main difference among the isotopes of the same element? (AS 1)
Answer:
The main difference between isotopes of the same element is
a) The number of neutrons is different.
b) Their physical properties are different but the chemical properties are similar.

Question 16.
For the following statements, write T for True and F for False. (AS 1)
a) J.J. Thomson proposed that the nucleus of an atom contains only nucleons.
b) A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.
c) The mass of an electron is 1836 times that of proton.
Answer:
a) False
b) False
c) True

Question 17.
Fill in the missing information in the following table. (AS 4)

Answer:

Question 18.
How do you appreciate the efforts made by scientists to explain the structure of atom by developing various atomic models? (AS 6)
Answer:

• Structure of atom, till today it is mysterious and challenging the scientists.
• We have to appreciate the scientists right from Lavoisier, who proposed law of conservation of mass, Proust who proposed law of constant proportions, John Dalton for his first model of atom, Rutherford for giving planetary model of atom and Neils Bohr for his model of atom.
• Till today scientists are trying to know the existence of more and sub-atomic particles besides electrons, protons and neutrons.
• Hence the efforts of scientists are highly appreciable, for making our lives comfortable and leaving many challenges before us to unveil or discover them.

Question 19.
Geeta got a doubt, “Why does atomic nucleus contain proton and neutrons? Why can’t electrons and neutrons be in it”. Can you help to clarify her doubt? Explain. (AS 1)
Answer:
Nucleus contains protons and neutrons inside it but not electrons and neutrons. If it would have happen, then

1. the alpha particles in the Rutherford’s alpha particle scattering experiment would have not been deflected or scattered.
2. the idea of nucleus would have not been evolved because the mass of electron is negligible, it is most unstable.

Question 20.
Collect information about various experiments conducted and theories proposed by scientists starting from John Dalton to Neils Bohr. Prepare a story with a title “History of atom”. (AS 4)
Answer:
History of atom
John Dalton proposed atomic theory based on law of conservation of mass and law of constant proportion as :

1. Atoms were indivisible.
2. Atoms of an element are all identical to each other and different from the atoms of other elements.

Later on various experiments conducted by Thomson, Goldstein, etc. proved that atom is divisible and consists sub-atomic particles like electrons, protons and neutrons. Based on this J.J. Thomson proposed a model of atom in 1898.

According to Thomson,

1. An atom is considered to be a sphere of uniform positive charge and electrons are embedded into it.
2. The total mass of the atom is considered to be uniformly distributed throughout the atom.
3. The negative and the positive charges are supposed to be balance out and the atom as a whole is electrically neutral.

This model is also called as plum pudding model or watermelon model.

Thomson’s student Ernest Rutherford conducted alpha particle scattering experiment and got the results which were not in favour of Thomson’s model. Based on his experiment, Rutherford proposed a model of atom. According to him,

1. All the positively charged material in an atom formed a small dense centre, called the nucleus of the atom. The electrons were not a part of nucleus.
2. Negatively charged electrons revolve around the nucleus in well – defined orbits like planets revolve around the sun.
3. The size of nucleus is very small as compared to the size of the atom.

This model could not account for stability of atom, as revolving electron must lose energy and eventually crash into the nucleus, as a result matter would not exist in the form that we see it now.

In 1913, Neils Bohr proposed another model to overcome Rutherford’s defect. According to Bohr,

1. Only certain special, discrete orbits of electrons are allowed in side the atom. These orbits or shells are called energy levels.
2. While revolving in these discrete orbits the electrons do not radiate energy and this helps that the electrons do not crash into the nucleus.
3. These orbits or shells are represented by K, L, M, N ………… or the numbers 1, 2, 3,

This model could not predict the spectra of atoms.

Hence this journey continues

9th Class Physical Science 5th Lesson What is inside the Atom? InText Questions and Answers

9th Class Physical Science Textbook Page No. 75

Question 1.
Why are the atoms of different elements different?
Answer:
Nature and properties of elements depends on the arrangement of atoms. We know that different elements behave differently. This is due to the difference in their atoms.

Question 2.
Is there anything inside atom that make them to be same or different?
Answer:
The arrangement of sub atomic particles inside the atom is responsible to make them to be same or different.

Question 3.
Are atoms indivisible?
Answer:
No, atom is divisible. There are many sub-atomic particles inside the atom according to the recent experiments.

9th Class Physical Science Textbook Page No. 77

Question 4.
If an atom consists of sub-atomic particles like protons, neutrons and electrons, how are they arranged in the atom ?
Answer:
The arrangement of sub-atomic particles like protons, neutrons and electrons has been explained by many scientists like Rutherford, Neils Bohr, etc. According to them, atom consists a central mass called nucleus. Nucleus consists protons and neutrons. Electrons revolve around the nucleus in fixed shells.

9th Class Physical Science Textbook Page No. 80

Question 5.
Why is atom stable?
Answer:
In an atom, the number of protons in the nucleus is equal to the number of electrons out side the nucleus. Hence the positive and negative charges in an atom are equal. So, atom is electrically neutral. So, atom is stable. But the stability of atom was explained by Neils Bohr in a different way.

Question 6.
Can you suggest any other arrangement of subatomic particles in the atom which prevents the revolving electron to fall into the nucleus?
Answer:
Electrons have to revolve around the nucleus in definite orbits such that the centripetal and centrifugal forces acting on the electron must be equal in magnitude and opposite direction. Then the revolving electron do not fall into the nucleus.

9th Class Physical Science Textbook Page No. 82

Question 7.
How many electrons can be accommodated in each shell of an atom?
Answer:
The number of electrons that can be accommodated in each shell of an atom depends on the shell number. First shell (K) consists 2 electrons, second (L) shell consists 8 electrons, third (M) shell consists 18 electrons, fourth shell (N) consists 32 electrons, and so on.

Question 8.
Can a particular shell have just one electron?
Answer:
No, shell has just one electron.

Question 9.
What is the criteria to decide number of electrons in a shell?
Answer:
The number of electrons in a shell can be decided by using a formula 2n². (Where n is shell number).

9th Class Physical Science Textbook Page No. 83

Question 10.
What is the valency of oxygen that you can calculate by the method discussed above?
Answer:

• Oxygen has 8 electrons in its atom. The distribution of electrons is 2, 6.
• The outer most shell consists 6 electrons, this number is hear to 8.
• Hence the valency of oxygen is 8 – 6 = 2.

9th Class Physical Science Textbook Page No. 85

Question 11.
Should we consider the number of neutrons as a characteristic of an atom?
Answer:
The mass of an atom which is a characteristic of an atom depends on the number of neutrons and protons that its nucleus contains. Hence the number of neutrons can be considered as a characteristic of an atom.

9th Class Physical Science Textbook Page No. 76

Question 12.
An atom is electrically neutral. But the electrons present in it are negatively charged particles. If only negative charges were present, the atom would not be neutral. Then, why are atoms considered to be neutral?
Answer:

• This is the idea before Rutherford’s model.
• According to Rutherford’s model, number of protons inside the nucleus and number of electrons outside the nucleus are equal.
• Hence the net negative charge is equal to net positive charge. So, the atom is electrically neutral.

9th Class Physical Science Textbook Page No. 80

Question 13.
Compare Rutherford and Thomson’s models of the atom on the following basis :
1) Where is the positive charge placed?
2) How are the electrons placed?
3) Are they stationary inside the atom or moving?
Answer:

1. According to Thomson, the positive charge is uniformly distributed throughout the atom. Whereas according to Rutherford, the positively charged protons are inside the nucleus.
2. According to Thomson, electrons are embedded in the positively charged atom, but according to Rutherford, electrons are revolving around the nucleus in welldefined orbits.
3. According to Thomson, electrons are stable inside the atom but according to Rutherford, electrons are moving inside the atom.

9th Class Physical Science Textbook Page No. 83

Question 14.
Phosphorus and sulphur show multiple valency. See table 2. Why do some elements show multiple valency? Discuss with your Mends and teachers.
Answer:

• For sulphur, the number of electrons in outer most orbit is 6.
• Hence the valency should be (8 – 6 =) 2.
• But sulphur exists in so many forms.
• In the excited state, these 6 electrons also tend to participate in the bond formation.
• Hence sometimes it shows the valency 6. Ex : SO₂, SO₃, etc.
• Same situation happens for phosphorus. Ex . PCl₃, PCl₅, etc.

9th Class Physical Science 5th Lesson What is inside the Atom? Activities

Activity – 1

Question 1.
Sketch the structure of atom as you imagine.

We learnt about electron, proton and neutron.
a) Suppose you had to arrange them in an atom, how do you do it?
Answer:
Many arrangements are possible. Think that atom looks like a room, we can arrange the particles in alternating rows.

b) In how many ways can you arrange these sub-atomic particles in a spherical shape?
Answer:
Protons are positively charged, electrons are negatively charged and neutrons are
neutral. Hence neutrons and protons can be kept nearer and electrons can be kept farther or near the edge of the sphere. This is only an assumption. We can arrange in so many ways like this.

AP State Syllabus AP Board 9th Class Physical Science Solutions Chapter 9 Floating Bodies Textbook Questions and Answers.

AP State Syllabus 9th Class Physical Science Solutions 9th Lesson Floating Bodies

9th Class Physical Science 9th Lesson Floating Bodies Textbook Questions and Answers

Improve Your Learning

Question 1.
A solid sphere has a radius of 2 cm and a mass of 0.05 kg. What is the relative density of the sphere? (AS 1)
Answer:
Radius of the sphere = 2 cm

Question 2.
A small bottle weighs 20 g when empty and 22 g when filled with water. When it is filled with oil it weighs 21.76 g. What is the density of oil? (AS 1)
Answer:
Weight of water = 22 – 20 = 2 gm
Weight of oil = 21.76 – 20 = 1.76 gm

Question 3.
An ice cube floats on the surface of a glass of water (density of ice = 0.9 g/cm3). When the ice melts will the water level in the glass rise? (AS 1)
Answer:
Yes, the water level rises.

Reason :
The ice cube floats on water, because its density is less than the density of water. When ice cube melts, it becomes water, so that the water level rises.

Question 4.
The volume of 50 g of a substance is 20 cm³. If the density of water is 1 g/cm³, will the substance sink or float when placed on the surface of water? What will be the mass of water displaced by the substance? (AS 1)
Answer:

∴ Weight of the water displaced by the substance = 20 g

Question 5.
Find the pressure at a depth of 10 m in water if the atmospheric pressure is 100 kPa. [1Pa = 1 N/m²] [100kPa = 10⁵ Pa = 10⁵ N/m² = 1 atm.] (AS 1)
Answer:
Depth ‘h’ = 10 m ; Atmospheric pressure P₀ = 100 kPa
Density of water p = 1 gm/cm³ = 1 kg/m³
Pressure at a depth ‘h’ is P = P₀ + hρg
= 100 + 10 x 1 x 9.8
= 100 + 98
= 198 kPa

Question 6.
Why do some objects float on the water? And some sink? (AS 1)
Answer:

• Floating or sinking of objects on water depends on two factors.
  a) Relative density
  b) Weight of the water displace by the object
• If the relative density of an object is greater than 1, the object sinks otherwise it floats.
• Eventhough the relative density is greater than 1, if the weight of the water displaced by the object equal to the weight of the object itself, the object floats on the water.

Question 7.
Explain density and relative density and write their formulae. (AS 1)
Answer:
Density :
Density is defined as mass per unit volume.
Density = \(\frac{\text { Mass }}{\text { Volume }}\)

Unit of density is gm/cm³ or kg/m³.

Relative density :
Relative density of an object is the ratio of density of the object to the density of water.

Question 8.
What is the value of density of water? (AS 1)
Answer:
Value of density of water = 1 gm/cm³ (or) 1 kg/cm³.

Question 9.
Find the relative density of wood. Explain the process. (Lab Activity 1) (AS 3)
Answer:
Aim :
To find the relative density of wood.

Materials required :
Overflow vessel, 50 ml measuring cylinder, spring balance, wooden block, water.

Procedure:

1. Weigh the 50 ml measuring cylinder and note its weight.
2. Weigh the wooden block and note its weight.
3. Pour water in the overflow vessel until it starts dripping from its beak.
4. When water stops dripping from the beak, place the 50 ml measuring cylinder under it.
5. Slip the wooden block gently into the overflow vessel, ensuring that the water does not splash out.
6. Once the wooden block is in the overflow vessel, water flows out of the beak and collects in the 50 ml cylinder.
7. Wait till the flow of water from beak, stops.
8. Weigh the cylinder with the water that overflowed and record the weight.

Question 10.
Which is denser, water or milk? (AS 2)
Answer:
The density of water is 1 gm/cc and that of milk is 1.02 gm/cc. Hence milk is slightly denser than water.

Question 11.
What is buoyancy? (AS 1)
Answer:
Buoyancy is the upward force that a fluid exerts on an object less denser than itself.
(or)
Buoyancy is the ability of an object to float in a liquid.

Question 12.
Classify the following things into substances having relative density > 1 and relative density < 1. Wood, iron, rubber, plastic, glass, stone, cork, air, coal, ice, wax, paper, milk, kerosene, groundnut oil, soap. (AS 1)
Answer:

Relative density > 1	Relative density < 1
Iron	Wood
Glass	Rubber
Stone	Plastic
Milk	Cork
Soap	Air
	Coal
	Ice
	Wax
	Paper
	Kerosene
	Groundnut oil

Question 13.
How can you appreciate the technology of making ships float, using the material which sink in water? (AS 6)
Answer:

• We know that a piece of iron sinks in water.
• The relative density of iron is 8.5 which is many times more than water.
• A ship that floats on water is made up of tonnes of iron. It is really wonderful.
• According to the Archimedes principle of buoyancy, any object can float when its weight is equal to the weight of water displaced by it.
• Hence ships are made with a larger surface area so that it displaces the water, whose weight is equal to the weight of loaded ship.
• It involves very sharp scientific calculations and a large engineering technology.
• Really such type of technologies are highly appreciable and the scientists who formulates all these are also really great.

Question 14.
Can you make iron float? How? (AS 3)
Answer:
Yes, we can make iron to float on water.
Procedure:

1. Take a piece of iron and drop it in a vessel of water.
2. We observe that the iron piece sinks in water.
3. Take a thin foil of iron and fold it into four folds.
4. Drop it in water. It sinks.
5. Now unfold the foil and bend it in the form of a bowl. [You can use an iron tin also]
6. Now drop the bowl in water.
7. If floats on water.

Reason:
The weight of water displaced by iron bowl (iron tin) is less than the weight of the iron bowl (iron tin).

Question 15.
How can you find the relative density of a liquid? (Lab Activity – 2) (AS 3)
Answer:
Aim :
To find the relative density of a liquid.

Materials required :
Small bottle of 50 ml capacity (the bottle should weigh not less than 10 gm), spring balance, any liquid (milk or oil or kerosene) about 50 ml.

Procedure:

1. Find the weight of empty 50 ml bottle.
2. Fill the bottle with water and weigh it.
3. Find the weight of 50 ml water.
4. Remove water from the bottle and fill it with any liquid (say milk).
5. Weigh the bottle with liquid.
6. Weight of 50 ml liquid = Weight of bottle with liquid – Weight of empty bottle

Question 16.
Find the relative density of different fruits and vegetables and make a list. (AS 3)
Answer:

• Follow the procedure in Q.No (11) of A.S – (3).
• Use different fruits and vegetables in the place of wooden block.
• Write the observed values in the following table.

Name of the fruit or vegetable	Relative density
Cabbage	0.36
Cauliflower	0.26
Bottleguard	0.56
Potato	0.67
Onion	0.59
Chilli	0.29
Bitterguard	0.4
Apple	1.22
Grape	1.04
Orange	0.34

Question 17.
Make a lactometer with ball point refill. What would you do to make the refill stand vertically straight? (Activity – 2) (AS 5)
Answer:

• Take an empty ball pen refill. It should have a metal point.
• Take a boiling tube and fill it with water.
• Put the refill in with metallic point inside the water.
• Use a pen to mark the point on the refill to show the part which is above the water surface.
• Pour out the water from the boiling tube and fill it with milk.
• Float the refill in the milk.
• Puf the record mark on the refill, at the point showing the part which is above the surface of the milk.
• These two marks are not at the same place. This is the improvised lactometer.
• We have to attach a small weight at the bottom of the refill to make it stand vertically straight.

Question 18.
Draw the diagram of a mercury barometer. (AS 5)
Answer:

Question 19.
Write a note on Pascal’s discovery in helping to make hydraulic jacks. (AS 6)
Answer:
Pascal’s principle:
External pressure applied to an enclosed body of fluid is transmitted equally in all directions throughout the fluid volume and the walls of the containing vessel.

Use :

1. This principle is used in designing and working of hydraulic jacks.
2. Hydraulic jacks are useful to lift heavy objects like cars and other vehicles in automobile work shops when the vehicles are to be required or repaired.
3. Here very less force is used to lift such heavy vehicles.

Appreciation :

1. Hydraulic jacks are used not only in automobile work shops, but also in so many industries where heavy weights are to be lifted with a little force.
2. All the comforts which we are enjoying now are the efforts of scientists who discovered the laws and principles.
3. Hence we have to appreciate the efforts of Pascal for his contribution in designing these principles.

Question 20.
Write a note on Archimedes discovery of force of buoyancy. (AS 6)
Answer:
Archimedes principle:
When a body is immersed in a fluid, it experiences an upward force of buoyancy equal to the weight of fluid displaced by the immersed portion of the body.

Use :
The principle is used to determine the purity of metals.

Appreciation :

1. This principle was discovered by Archimedes eventually when he was taking bath.
2. With this principle he could solve the problem assigned by the king to him.
3. So many problems in our life may be solved by so many scientific principles discovered by various scientists.
4. You might have heard about falling of the statue of Budha in Hussain Sagar.
5. That statue was lifted by using the principle of buoyancy.
6. Archimedes is thought to be so important as a mathematician that scientists honoured him.
   a) A large hole or crator on the moon is named after Archimedes.
   b) Some mountains on the moon are called the monte – Archimedes.
7. Hence the efforts of Archimedes in discovering such type of principle may be highly appreciated.

Question 21.
You found the relative densities of some solids and some liquids by doing some activities. List the solids and liquids in increasing order of relative density. (AS 4)
Answer:

Substance	Relative density
Kerosene	0.81
Rubber	0.94
Milk	1.02
Glass	1.29
Iron	8.5

Question 22.
Iron sinks in water, wood floats in water. If we tie an iron piece to wood piece of the same volume, buritlle and drop it in water, would bundle sink or float? Make a guess and find out whether your guess is correct or wrong with an experiment. Give reasons. (AS 2, AS 3)
Answer:
The body sinks in water.

Reason :
The combined mass of the system increases, so the combined density also increases. Hence the body sinks in water.

Question 23.
Air brakes in automobiles work on Pascal’s principle. What about air brakes? Collect the information about the working process of air brakes. (AS 4)
Answer:

• Air brakes works on the principle of conversion of energy. Generally in trains, while it is moving -fit .produces kinetic energy. This kinetic energy has to be reduced to make the train stop. Here air is used to reduce kinetic energy by converting it into heat energy.
• The system of air brakes in trains has been shown in the figure.
• The important parts are compressor, main reservoir, driver’s brake value, brake pipe, triple value, auxiliary reservoir, brake cylinders, and brake block.

Working:

1. When the driver placed the value in application position, the air pressure in the brake pipe escapes.
2. The loss of pressure is detected by the slide value in the triple value.
3. Now a connection between the auxiliary reservoir and the brake cylinder has been opened and the air in the auxiliary reservoir feeds through into the brake cylinder.
4. The air pressure forces the piston to move against the spring pressure and causes the brakes to be applied to the wheels.

Question 24.
Where do you observe Archimedes principle in daily life? Give two examples.
Answer:
Daily life application of Archimedes principle :

1. Archimedes principle of buoyancy is applied in our daily life in many ways.
2. Fish, human swimmers, ice bergs and ships float follow Archimedes principle of buoyancy.
3. Rise of balloon in air also follows Archimedes principle.
4. While dragging water from a well, the bucket filled with water seems to be weightless till it reaches the surface of the water in the well. This is also due to buoyancy.
5. Swimming of duck in water is also an example of Archimedes principle.

Question 25.
Where do you observe Pascal’s principle in daily life? Give a few examples.
(OR)
Write any one application of Pascal’s principle in daily life.
Answer:
Daily life application of Pascal’s principle :
Pascal’s principle is applied in the working of

1. Hydraulic jacks
2. Hydraulic lifts
3. Hydraulic pumps
4. Hydraulic cranes
5. Siphons
6. Artesian wells
7. Water towers and dams

9th Class Physical Science 9th Lesson Floating Bodies InText Questions and Answers

9th Class Physical Science Textbook Page No. 141

Question 1.
a) Did kerosene float above the water or did water float above the kerosene?
Answer:
Kerosene floats above the water.

b) Which objects float in kerosene?
Answer:
Plastic buttons, match stick, tiny paper balls, wax, etc. floats in kerosene.

c) Which objects sink in kerosene but float on water?
Answer:
Wax sink in kerosene but float on water.

d) Which objects sink in water?
Answer:
Pins, small pebbles, sand, etc. sink in water.

e) Draw a diagram of the tube, showing the results of your activity.
Answer:

f) Why did different objects behave differently?
Answer:
The density of objects is the main reason to behave differently.

9th Class Physical Science Textbook Page No. 144

Question 2.
1) What is the relative density of wood?
Answer:
0.8

2) What is the relative density of glass?
Answer:
1.2

3) Which is denser, rubber or plastic?
Answer:
Rubber is denser than plastic.

4) Which is denser, wood or cork?
Answer:
Wood is denser than cork.

5) Do objects that have a relative density less than 1 Sink in water or float on it?
Answer:
Float on water.

6) Do the objects that sink in water have a relative density less than 1 or more than 1?
Answer:
More than 1.

7) Classify the above materials as denser than stone and less denser than the stone.
Answer:
Denser than the stone : iron, nails.
Less denser than the stone :
eraser, wood, glass slides, plastic cube, Aluminium, glass marbles, cork.

8) What relationship do you find between the relative density of objects and floating sinking of the objects?
Answer:
If the relative density is less than 1 the object of less density will float above the other in the water.

9th Class Physical Science Textbook Page No. 145

Question 3.
1) Which liquid will float on top if groundnut oil is poured over water?
Answer:
Groundnut oil float on the water.

2) If we put a wooden block in kerosene, will it float or sink? Give reasons for your answer.
Answer:

• Wooden block will sink in the kerosene.
• Because, the density of the wooden block is more than the kerosene.

3) A piece of wax floats in water but the same piece of wax sinks in a liquid say liquid ‘X’. Will the relative density of liquid . ‘X’ be less than 1 or greater than 1? How can you say?
Answer:

• The relative density of liquid ‘X’ is less than 1.
• The density of wax is less than 1 because it floats on the water.
• The density of liquid ‘X’ is less than the density of the wax this means less than 1. because wax sinks in that liquid ‘X’.

4) If we mix some water in milk, will the relative density of the mixture be less than or more than the relative density of milk?
Answer:

• We know that relative density of milk is more than 1 and density of milk is more ‘ than water.
• If we mix some water in milk, the density of the mixture will decreases and the relative density will also be less than the relative density of milk.

5) If we take two bottles of equal volume and pour pure milk in one and milk mixed with water in the other, which one will be heavier?
Answer:

• Pure milk is heavier than water mix milk.
• This is due to density of milk is more than water.

9th Class Physical Science Textbook Page No. 151

Question 4.
Why is the height of mercury column nearly 76 cm in the tube?
Answer:
Air pressure is the weight of air in the atmosphere above the reservoir (bowl of mercury). So, the level of mercury continues to change until the weight of mercury in the glass tube is exactly equal to the weight of the air above the reservoir, which is 76 cm.

9th Class Physical Science Textbook Page No. 154

Question 5.
What happens if we replace this cylindrical liquid column with another object which is made up of a material whose density is equal to the density of liquid?
Answer:
We know that the pressure difference in the liquid,
P₂ – P₁ = hρg

Since F = PA and W = mg
We get F = W (Values of displaced liquid)

1. Here F’ is the force applied on the object and ‘W’ is the weight of the liquid.
2. So, the”force applied on the object by the liquid is equal to the weight of the displaced liquid.

9th Class Physical Science Textbook Page No. 155

Question 6.
Why does the stone lose weight when it is immersed?
Answer:

• Suspend a stone from a spring balance. Note the reading of the spring balance.
• Take a beaker half-filled with water.
• Now immerse the stone in the water, note the reading of the spring balance.
• We notice that the stone, when immersed appears to lose some weight.
• The immersed stone appears to lose weight because the force of buoyancy.
• Thus the apparent loss of weight must be equal to the force of buoyancy acting on the immersed stone.

9th Class Physical Science Textbook Page No. 142

Question 7.
Let us suppose you have two blocks and you do not know what material they are made of. The volume of one block is 30 cm3 while the other is 60 cm3. The second block is heavier than the first. Based on this information, can you tell which of the two blocks is denser?
Answer:
No, we cannot say which of the two blocks is denser, because any one of the quantity
i. e., either volume or weight must be same.

9th Class Physical Science Textbook Page No. 153

Question 8.
a) What would happen if Toricelli’s experiment is done on moon?
b) A stopper is inserted in the small hole of the glass tube of the mercury barometer below the top level of the mercury in it. What happens when you pull out the . stopper from the glass tube?
c) Why don’t we use water instead of mercury in Toricelli experiment? If we are ready to do this experiment, what length of tube is needed?
d) Find the weight of the atmosphere around the earth (take the radius of earth as 6400km)
Answer:
a) If Toricelli’s experiment had been done on moon, the height of mercury column will be zero. Because there is no atmosphere on the moon.

b) The mercury level does not change, because there is vacuum above the mercury level. Hence no pressure is on the mercury. Also, the weight of mercury column must be equal to the air pressure above the reservoir. Hence there will be no change in the height of the mercury column.

c) We cannot use water instead of mercury in Toricelli experiment because, if we want to use water, we have to take the glass tube of length nearby above 10 m, which is inconvenient.
If water is taken,
P₀ = ρhg
1 01 yin5
1.01 × 10⁵ = 1 × 10³ × h × 9.8 ⇒ h = = 0.1030 × 10² = 10.3 m

d) Weight of atmosphere = Atmospheric pressure x Surface area of the earth

9th Class Physical Science Textbook Page No. 157

Question 9.
a) Why is it easier for you to float in saltwater than in freshwater?
b) Why is there no horizontal buoyant force on a submerged body?
c) Two solid blocks of identical size are submerged in water. One block is iron and the other is aluminium. Upon which is the buoyant force greater?
d) A piece of iron when placed on a block of wood, this makes the wood to float lower in the water. If the iron piece is suspended beneath the wood block, would it float at the same depth? Or lower or higher?
Answer:
a) Salt water is denser than freshwater.
b) Buoyant force is the upward force only. The body is submerged means, its weight is more than the buoyant force. Here there will be no horizontal buoyant force.
c) Buoyant force on iron block is more than that of aluminium block.
d) It floats on higher depth than in the first case.

9th Class Physical Science 9th Lesson Floating Bodies Activities

Activity – 1

Question 1.
Comparing density – relative density.
Take two test tubes of the same size and fill one to the brim with water and the other with oil.
a) Which will weigh more?
Answer:
The test tube with oil will weigh more.

b) Which liquid is denser?
Answer:
Oil is denser than water.
Take two equal sized blocks made of wood and rubber.

c) Which of these two blocks is heavier?
Answer:
Wooden block is heavier.

d) Which one is denser?
Answer:
Wooden block is denser than rubber.

Activity – 3

Question 2.
Do the objects denser than water float in it? Prove it with an activity.
Answer:

• Collect some objects listed in the table below.
• Place them one by one in a glass of water and observe whether they sink or float in water.
• Record your observations in the table.

Observations:

• Find the relative densities of all the objects.
• We observe that some objects floats and some objects like iron nail, glass marble, stone sinks in water.
• Geometry box made of iron floats on water, though its relative density is greater than 1. This is due to its larger surface area.
• Geometry box made of iron floats on water though it is made up of a substance denser than water.
•  We can say that the floating or sinking of an object does not depend not only on its relative density, but also its surface area which displaces the water.

Activity – 4

Question 3.
Show that for a floating object, the weight of the object is equal to the weight of water displaced by it.
Answer:

• Take a beaker and weigh it. Note down its weight.
• Fill water in an overflow jar, wait until the water stops dripping from the outlet of the overflow jar.
• Now place the beaker below the outlet of the overflow jar.
• Take a wooden block, moisten it with water and gently drop it into the overflow jar.
• Water will flow out of the overflow jar and collects in the beaker kept under the overflow jar.
• Measure the weight of beaker with water.
• Subtract the weight of beaker from this. The value gives the weight of water displaced by wooden block. Note it.
• Now remove wooden block from the overflow jar, make it cry and weight.
• We can observe that the weight of wooden block is equal to weight of water displaced by it.
• Do the same experiment with some other substances and record your observations in the table.

Activity – 5

Question 4.
Explain how does metal aluminium floats on the water with an activity.
Answer:

• Take a small sheet of aluminium foil.
• Fold it four or five times, pressing the foil tight after each fold.
• We can find that the aluminium foil will sink in the water.
• Now unfold the aluminium foil and make it as a small bowl.
• We can find that the bowl will float on the water.
• The metal bowl displace larger amount of water than a metal piece.
• Weight of the displaced water is more than the metal sheet.
• So, bowl will float on the water.

Activity – 6

Question 5.
Prove that the water exerts upward force on objects.
Answer:

1. Take an empty plastic bottle.
2. Put the cap on it tightly.
3. Place the bottle in a bucket of water.
4. The bottle will float.
5. Push the bottle into the water by your hand as shown in figure.
6. We feel some upward force.
7. Try to push it further down. We feel increase in the upward force.
8. Now release the bottle.
9. It bounce back to the surface of water.
10. Here the upward force of water a real, observable force.
11. This force acting on unit area of the surface of an object is called static pressure of the water.

Activity – 7

Question 6.
Describe an activity to observe the air pressure.
Answer:

1. Take a glass tumbler.
2. Stick some cotton at the bottom of it.
3. Immerse it inversely in water upto the bottom of the container as shown in figure.
4. Take out the tumbler from water.
5. We observe that the cotton attached at the bottom of the tumbler is not wet.
6. This is due to the force of air which is applied on water by the air present in the tumbler and stops water from entering the tumbler.
7. This force on unit area of water is the pressure of air.

Activity – 8

Question 7.
How can you measure the force of buoyancy and how much?
(OR)
Why does and stone lose weight when it is immersed in water?
Answer:

• Suspend a stone from a spring balance.
• Note that the reading of the spring balance.
• The reading gives the weight of the stone.
• Take a beaker half filled with water.
• Now immerse the stone in the water.
• Note the reading of the spring balance.
• The reading gives the weight of the immersed stone.
• We may notice that the stone, when immersed, appears to lose some weight.
• The immersed stone appears to lose weight because the force of BUOYANCY, exerted on the stone by the water in the upward direction.
• Thus the apparent loss of weight must be equal to the force of buogancy acting on the immersed stone.
• The lose of weight of stone is equal to weight of the water displaced by the stone, this is the force of buoyancy.

Activity – 9

Question 8.
‘State and prove Archimedes principle of buoyancy.
Answer:

Archimedes principle :
Archimedes principle states that when a body is immersed in a fluid, it experiences an upward force of buoyancy equal to the weight of fluid displaced by the immersed portion of the body.

Proof:

1. Suspend a stone from a spring balance.
2. Note the reading on the spring balance. This reading is the weight of the stone.
3. Take an overflow jar with water and place a graduated beaker below the beak as shown in the figure.
4. Now immerse the stone in the water and note the reading on the spring balance.
5. Measure the volume of the water that overflows into the graduated beaker.
6. The reading of the spring balance gives the weight of the immersed stone.
7. The beaker reading gives the volume of water displaced by the stone.
8. The difference in the two readings of spring balance gives the apparent loss of weight of the stone.
9. Now weigh the water in the graduated beaker.
10. We observe that the apparent loss of weight of the stone is equal to the weight of the water displaced by the stone.
11. Hence Archimedes principle is proved.

AP State Syllabus AP Board 9th Class Social Studies Important Questions Chapter 3 Hydrosphere.

AP State Syllabus 9th Class Social Studies Important Questions 3rd Lesson Hydrosphere

9th Class Social 3rd Lesson Hydrosphere 1 Mark Important Questions and Answers

Question 1.
How are we polluting oceans today? (SA-III: 2016-17)
Answer:
We are polluting oceans today by dumping plastic, other forms waste and other industrial waste.

Question 2.
How can you appreciate the oceans as resources? (SA-II: 2017-18)
Answer:

• Ocean waves are used for generating power.
• Ocean floor is mined for oils.
• Oceans also provide with gems and pearls.

Question 3.
Write any two factors that affect the salinity of oceans. (SA-II: 2018-19)
(OR)
Write any two factors which effect salinity in water bodies? (SA-I: 2018-19)
Answer:
Salinity in water bodies is affected by evaporation, precipitation, ice formation, ice melting and temperature also.

Question 4.
Give any two examples of warm ocean currents. (SA-I: 2019-20)
Answer:
Two examples of warm ocean currents :
(a) Gulf stream,
(b) Kuroshio

9th Class Social 3rd Lesson Hydrosphere 2 Marks Important Questions and Answers

Question 1.
(SA-I: 2019-20)
a) Water distribution on earth
b)Fresh water consumption by humans
a) What percentage of the total water on the Earth is available for consumption?
Answer:
0.75% or 2.5%

b) Which activity of humans need maximum water?
Answer:
Agriculture.

9th Class Social 3rd Lesson Hydrosphere 4 Marks Important Questions and Answers

Question 1.
Describe the stages of water cycle.(SA-II: 2017-18)
(OR)
Explain various stages of Hydrological cycle. (SA-I: 2018-19)
(OR)
Draw the hydrological cycle and describe the stages involved in it.

Answer:
There are six stages of water cycle. They are –
a) Evaporation :

• The process by which water changes from liquid to gas by using sun’s energy is called evaporation.
• Land, lakes, rivers and oceans send up a steady of water vapour and plants lose water to the air through transpiration.

b) Transportation :

• The movement of water through the atmosphere specifically from over the ocean to land in the form of clouds is transportation.
• Clouds are propelled from one place to another by either the jet stream, surfaces based circulations like land and sea breezes or other mechanisms.

c) Condensation :
The transported water vapour eventually condenses forming tiny droplets and clouds.

d) Precipitation :

• The primary mechanism for transporting water from the atmosphere to the surface of the earth is precipitation.
• When the clouds meet cool air over land precipitation is triggered in the form of rain, sleet or snow and thus water reaches the ground.

e) Run off:

• Most of the water which returns to land flows down hills as run off.
• Some of it penetrates into the land and charges ground water while the rest, as river flow, returns to the oceans where it evaporates.

f) Groundwater :
Under special circumstances, groundwater can even flow upward in artesian wells.

Question 2.

Rank	Ocean	Notes
1.	The Pacific ocean	Separates Asia and Oceania (Australia, New Zealand, Papuva, New Guinia together) from the Americas.
2.	The Atlantic ocean	Separates the America from Europe and Africa.
3.	The Indian ocean	Washes upon Southern Asia and separates Africa and Australia.
4.	The Antarctic ocean (Southern ocean)	Sometimes considered an extension of the Pacific, Atlantic and Indian oceans which encircles Australia.
5.	The Arctic ocean	Sometimes considered a sea of the Atlantic, which covers much of the Arctic and washes upon North America and Eurasia.

Read the above table and answer the following questions. (SA-II: 2017-18)
1. Which ocean is also known as Southern Ocean?
2. Which ocean separate the America from Europe and Africa?
3. Which continents are separated by the Indian Ocean?
4. What are the land masses in Oceania?
Answer:

1. Antarctic ocean is know as Southern ocean.
2. The Atlantic ocean separates the America from Europe and Africa.
3. The Indian ocean washes upon Southern Asia and separates Africa and Australia.
4. Australia, New Zealand, Papua New Guinea are the land masses in Oceania.

Question 3.
“Water is considered a renewable resource”. Explain this statement.” (SA-I: 2019-20)
Answer:

• Water is considered a renewable resource because it cycles through the Earth system.
• It falls as precipitation.
• Then gets absorbed or run off.
• If it is absorbed, it can go deep into the ground or it can be taken up by plants.
• Plants return water to the atmosphere through transpiration.
• The water that goes deep into the ground can eventually run off into surface bodies of water like lakes and streams.
• The water that runs off can be evaporated, or it can run into lakes and streams.
• The water in lakes and streams can be evaporated, returning it to the atmosphere, where it can precipitate again.

9th Class Social 3rd Lesson Hydrosphere Important Questions and Answers

Question 1.
What is an Ocean? Write a brief essay on the ocean.
Answer:
The huge water bodies are called Oceans. There are five oceans on the earth. They are the Pacific ocean, the Atlantic ocean, the Indian ocean, the Southern (Atlantic) ocean and the Arctic ocean.

The ocean basins are in many ways similar to the land surface. There are submarine ridges, plateaus, canyons and terraces. Ocean floor is simply divided into four layers. They are continental shelf, continental slope, deep sea plain and oceanic deep.

Ocean water is salty. Most of the salt in the oceans comes from land. Over millions of years rain, rivers and streams have washed over rocks containing the compound Sodium Chloride and carried into the sea. The total content of dissolved salts in sea water is called salinity. It is usually expressed as parts per thousand (PPT). Average salinity of the oceans is 35%0. The salinity of ocean water depends mainly on evaporation and precipitation.

The little variations in ocean temperature show great effect on land temperatures. South west monsoon in India is affected by ‘El Nino’ and ‘La Nino’. These are the effects caused by the changes in temperature in the Pacific ocean. Normally, the temperature in oceans varies from – 2°C to 29°C.

The general movement of a mass of water in a fairly defined direction over great distance is called an ocean current. Based on temperature ocean currents may be classified into cold currents and warm currents. Generally warm currents flow towards the poles, cold currents flow towards the equator. Centrifugal force, effects of winds, effects of precipitation, effect by solar energy are the causes of ocean currents.

Oceans have many uses for man. They are the store houses of fish. Oceans are the sources of Chlorine, Fluorine, Bromine and Iodine. Tides and waves of the oceans are the sources of renewable energy. Oceans are sources for rainfall. They act as international highways. Rock petroleum and natural gas are extracted under oceans. Minerals such as sand, gravel, manganese, copper, nickel, etc., are mined from oceans.

Thus without oceans Ijfe of man is impossible.

Question 2.
Describe the salinity of the oceanic water.
Answer:

• Ocean water is salty.
• Most of the salt in the oceans comes from land.
• Over millions of years rain, rivers and streams have washed over containing the compound Sodium Chloride (NaCl) and carried into the sea.
• The total content of dissolved salts in sea water is called salinity.
• The salinity of oceanic water depends mainly on evaporation and precipitation.
• In coastal regions salinity is influenced by the fresh water flow from rivers.
• In polar regions salinity is influenced by the process of freezing and thawing of ice.
• Salinity is usually expressed as parts per thousand (%0) or PPT.
• The average salinity of the oceans is 35%0.
• Lake Van of Turkey is the water body with the highest salinity.

Question 3.
Describe the temperature of oceanic water.
Answer:

• When compared to land the temperature on oceans does not show more variations.
• Ei Nino and La Nino are the effects caused by the changes in temperature in the Pacific Ocean.
• The activeness of South West monsoon in India is affected by Ei Nino and La Nino.
• The ocean temperature is influenced by latitudes, winds and ocean currents, unequal distribution of land and the change of seasons.
• Normally, the temperature in oceans varies from – 2°C to 29°C.
• The highest temperature is recorded in inland seas.
• The temperature is the highest in Red Sea, i.e. 38° C.
• As one goes deep inside the oceans, the temperature rapidly decreases for every 1 km and remains stable.
• The temperature is stable at the foot of ocean i.e., 1.8° C.

Question 4.
What are the ocean currents? How are they formed?
Answer:
1. The general movement of a mass of water in a fairly defined direction over great distance is called ocean current.

2.Causes that lead to the formation of ocean currents are :
a) Centrifuge! Force :
The centrifugal force at the equator is greater than that at the poles. The variation of these forces makes the equatorial water to move towards the poles.

b) Effect of Winds :
The stresses due to wind and the wind movement modifies the the theoretical direction of currents. Due to the frictional gliding of winds water is dragged along the wind direction. Thus a 50 miles per hour wind will produce a current whose velocity is 0.75 miles per hour.

c) Effect of Precipitation :
Since the level of sea is higher water moves north and south from the equator.

d) Effect of Solar Energy :
Heating by solar energy causes the water to expand near the equator. Hence near the equator the ocean water is about 8 cm higher in level than in the middle latitudes. This causes a very slight gradient and water tends to flow down the slope.

e) Salinity, density differences, melting of ice also affect the ocean currents.

Question 5.
How are the oceans useful to mankind?
Answer:

1. Oceans are store houses for fish.
2. Since early times man depended on oceans for food.
3. Dogger Bank North Sea, Grand – bank, New found land are famous fishing regions.
4. Chlorine, Fluorine, Bromine and Iodine are found in oceans.
5. Tides and waves are non-renewable energy resources.
6. Oceans are sources for rainfall.
7. Oceans act as international highways.
8. Sources for civilizations : Greek civilization, Rome civilization all flourished on banks of rivers and oceans.
9. Rock petroleum, Natural gas are extracted under oceans.
10. Oceans are mined for minerals, salt, sand, gravel, manganese, copper, nickel, etc.

Question 6.
Why is the earth called the blue planet?
Answer:

• Planet earth is called the ‘Blue planet’ due to the abundant water on its surface.
• About 71% of the earth is covered with water.
• If we look at earth from outer space, we can see the earth almost entirely blue.

Question 7.
What is the importance of continental shelf?
Answer:

1. The continental shelf with depth up to 200 mts occupied about 7.6% of the oceans area.
2. It is the border zone between land and sea.
3. Continental shelf is most important to
   a) Fish wealth is more in this region.
   b) Rock petroleum, natural gas are found here.
   c) Building sea port is possible here.

Question 8.
What are Oceans?
Answer:
The huge water bodies are called Oceans.

Question 9.
What is ocean current?
Answer:
The general movement of a mass of water in a fairly defined direction over great distance is called ocean current. –

Question 10.
What is meant by evaporation?
Answer:
Evaporation: The process by which water changes from liquid to gas by using sun’s energy is called evaporation.

Question 11.
What is meant by transportation?
Answer:
Transportation:
The movement of water through the atmosphere specifically from over the ocean to land in the form of clouds is called transportation.

Question 12.
Where do we find trenches? What is their significance?
Answer:

• Contrary to our expectations, most of the deepest trenches are not located in the midst of oceans.
• They are found more close to the continents.
• They are very significant in the study of plate movements.

Question 13.
Which part of ocean floor is suitable for building seaport? Why?
Answer:

• Continental shelf of ocean floor is suitable for building seaport.
• The continental shelf with depth upto 200 m.
• It is the border zone between land and sea.
• It will be useful in anchoring the ships.

Question 14.
Do you think the rain we get is in any way related to hydrological cycle?
Answer:

• Yes. I think the rain we get is related to hydrological cycle.
• It is a part of precipitation, which constitutes in hydrological cycle.
• It is the fourth stage of the six stages in hydrological cycle.

Question 15.
What are the factors that affect the movement of ocean currents?
Answer:
The factors that affect the movements of ocean currents are –

1. The centrifugal force
2. The winds
3. The precipitation
4. The solar energy
5. Salinity
6. Differences in density
7. Melting of ice etc.

Question 16.
Write about continental slope.
Answer:

• The continental slope is spread from 200 mts to 3000 mts depths of oceans.
• It comprises of 15% of the ocean area.
• Submarine canyons are observed in this region.

Question 17.
Write about the classification of Ocean currents.
Answer:
1. Ocean currents may be classified on the basis of temperature as –
(a) Cold Currents
(b) Warm Currents

2. Ocean currents may be classified on the basis of speed as –
(a) a stream
(b) a drift

Question 18.
“From ail the sources of water reaching the earth, less than 1% of water is useful to man” – Interpret the statement.
Answer:
Of the total volume of water on earth only 2.75% is fresh water. Most fresh occurs in the form of permanent ice, snow locked up in the Antarctica and Arctic and in the mountain regions. The principal sources of water for human use are lakes, rivers, soil moisture and relatively shallow ground water basin. The usable portion of these sources is only about less than 1% of all fresh water.

Question 19.
“RF = RO + ET” – Explain the equation.
Answer:

• The total amount of water present on the earth surface remains constant but undergoes continuous transformation from water vapour to liquid.
• This equation is also called water balance equation.
• That means the amount of water received from rainfall is equal to the total amount of water runs off and the amount of water that is lost in evapotranspiration.
• Thus the equation Total Rain Fall = Total Run Off+Total water lost in Evapotranspiration.

Question 20.
in which ways oceans are being exploited by us, today?
Answer:

• Today oceans have also fallen victim to our exploitation.
• Many large fish like whales have been disappearing.
• Oceans have also become dumping ground for our plastic and other forms of faste.

Question 21.
Usually oceans have salinity of 35%. But being part of Atlantic ocean, how come Baltic sea has salinity of 3-15%?
Answer:

1. Baltic sea is enclosed by Scandenavia (Norway, Sweden), Finland, Baltic countries and North European plain.
2. It has major inflows from rivers like Oder, Vistula, Neva, Narva, Jome, Neman, Kemijoki and Dangava.
3. Only outlets towards danist areas.
4. As its coastal regions are in respect of fresh waters resulting in lower salinity.

Question 22.
Lake Van of Turkey experiences harsh winters with -300C. Why do you think its water never gets freezed?
Answer:

• Lake Van is fed by streams descending from surrounding mountains.
• It has no outlet, as outlet once present was closed by volcanic eruption.
• Water here is with a pH value of 9.7 – 9.8.
• It is situated at an altitude of 5380 ft.
• But because of its salinity of 330%, (oceans have 35% salinity) it is free from freezing.

Question 23.
The table below shows the descending order of the oceans in terms of size.

Rank	Ocean	Notes
1.	The Pacific ocean	Separates Asia and Oceania (Australia, New Zealand, Papuva, New Guinia together) from the Americas.
2.	The Atlantic ocean	Separates the America from Europe and Africa.
3.	The Indian ocean	Washes upon Southern Asia and separates Africa and Australia.
4.	The Antarctic ocean (Southern ocean)	Sometimes considered an extension of the Pacific, Atlantic and Indian oceans which encircles Australia.
5.	The Arctic ocean	Sometimes considered a sea of the Atlantic, which covers much of the Arctic and washes upon North America and Eurasia.

1) What is the largest ocean on the earth?
Answer:
The Pacific ocean.

2) Which ocean is considered as the extension of three important oceans?
Answer:
The Antarctic ocean.

3) What is the smallest ocean on the earth?
Answer:
The Arctic ocean.

4) Which ocean separates America from Europe and Africa?
Answer:
The Atlantic ocean.

5) Where is the Indian Ocean?
Answer:
To the South of Asia.

Question 24.
“The activeness of South west monsoon in India is affected by El Nino and La Nino”. Prove the statement.
Answer:

• El Nino and La Nino are the names given to the changes in winds in the Pacific Ocean.
• El Nino and La Nino are formally called ‘The small boy’ and ‘The little girl’.
• La Nino and El Nino come about when the waters of the eastern and central Pacific Ocean along the equator become usually cold or warm.
• These changes in the Pacific produce swings in atmospheric pressure, winds, temperature and rainfall that have a global impact.
• For India La Nino is often a cause for concern because of its adverse impact on the South west monsoon.
• The El Nino on the other hand is often beneficial for the monsoon especially in the latter half of the season.
• Because of global warming the temperature of the western Pacific is influencing the effect La Nino.

News Item : ELNINO may affect the monsoon :                                                 4-8-2017 (BUSINESS STANDARD) The Indian Meteorological Department scaled down its full season forecast for the South west monsoon this year from normal to deficient, the first indication of a drought in several parts of the country. The Director General L.S. Rathore in an interview says though rains in August may be normal the intensity may decline in September.

Question 25.
Can you say what the temperature at the foot of the Pacific ocean is?
Answer:

• Normally, the temperature in oceans varies from -2°C to 29°C.
• As one goes deep inside the oceans the temperature rapidly decreases for every 1 km and then it remains stable.
• The temperature is stable at the foot of the ocean, i.e. 1.8°C.
• Therefore the temperature at the foot of the Pacific ocean is 1.8°C.

Question 26.
“The government of Maldives held its first underwater cabinet meeting at a depth of 20 feet off the coast just north of the capital Male. Maldives wanted to attract the attention of the world to the dangers of global warming and sea-level rise. This is a matter of great concern not only for the Maldives but also for all the countries in the World”.
Basing on the information given above – frame a thought provoking question on the issue.
Answer:
What are the causes that lead to the sea level rise ? What should we do to prevent it?

Question 27.
Why do we call the earth as blue planet?
Answer:

• 71% of the earth is covered with water.
• Hence it appears as blue in the photographs taken from the moon.
• So we call the earth as blue planet.

Question 28.
Without oceans life of the man is impossible. Discuss it.
Answer:

• Oceans are international highways hence facilitate imports and exports among different countries.
• Oceans are sources of rainfall. Much of the evaporation takes place from oceans and comes to earth in the form of rainfall.
• They are the source of sea food which is staple food for some people.
• Oceans are warehouses of minerals like Petroleum, Natural Gas, Manganese etc., which are necessary for industrial development.

Hence life of the man is impossible without oceans.

Question 29.
Observe the map.

Now, answer the following questions.
1) Which ocean separates America from Africa and Europe?
Answer:
Atlantic ocean.

2) Name ocean that separates Africa and Australia.
Answer:
Indian ocean.

3) Which is the ocean that encircles Australia?
Answer:
Pacific ocean.

4) Which ocean is there to the south of India?
Answer:
Indian ocean.

Question 30.
Locate the following oceans in the world map given below.
1) The Pacific ocean
2) The Atlantic ocean
3) The Indian ocean
4) The Arctic ocean
5) The Antarctic Ocean
6) The Baltic sea
7) The Red sea

Question 31.
Describe any one impact of ocean currents for the region you live.
Answer:
The Indian Monsoon current refers to the seasonally varying ocean current regime found in the tropical regions of the nothern Indian ocean. The seasonally reversing open ocean currents that pass through south of India are referred to as the winter monsoon current and the summer monsoon current, alternately the north-east monsoon current and the southwest monsoon current.

India receives rainfall due to these currents.

Question 32.
Without oceans life of man is impossible. Discuss it.
Answer:
Throughout the history man is directly or indirectly influenced by the oceans. Oceans have many uses for man.

1. Since early times man depended on oceans for food. Oceans are store houses for fish.
2. Ocean is a source of valuable minerals. Chlorine, Fluorine, Bromine and Iodine are found in oceans.
3. Rock petroleum, Natural gas are extracted under oceans.
4. Oceans are mined for mineral salt, sand, gravel manganese, copper, nickel etc.
5. Some biological products of oceans are also commercially used. For example, pearls taken from oysters are used in jewellery.
6. Shells and corals have been widely used as source of building material.
7. Tides and waves are renewable energy sources.
8. Oceans are sources of rainfall.
9. Oceans act as international highways.
10. Many great civilizations such as Greek civilization, Rome civilization all flourished on the banks of rivers and oceans.

There are many more uses for man from oceans. Hence we can say without oceans life of man is impossible.

AP State Syllabus AP Board 9th Class Physical Science Solutions Chapter 3 Is Matter Pure? Textbook Questions and Answers.

AP State Syllabus 9th Class Physical Science Solutions 3rd Lesson Is Matter Pure?

9th Class Physical Science 3rd Lesson Is Matter Pure? Textbook Questions and Answers

Improve Your Learning

Question 1.
Which separation techniques will you apply for the separation of the following? (AS 1)
a) Sodium chloridfe from its solution in water.
b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride.
c) Small pieces of metal in the engine oil of a car.
d) Different pigments from an extract of flower petals.
e) Butter from curd.
f) Oil from water.
g) Tea leaves from tea.
h) Iron pins from sand.
i) Wheat grains from husk.
j) Fine mud particles suspended in water.
Answer:

Mixture	Separation technique
a) Sodium chloride from its solution in water	Crystallization
b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride	Sublimation
c) Small pieces of metal in the engine oil of a car	Filtration
d) Different pigments from an extract of flower petals	Chromatography
e) Butter from curd	Centrifugation
f) Oil from water	Separation funnel
g) Tea leaves from tea	Filtration
h) Iron pins from sand	Magnetism
i) Wheat grains from husk	Winnowing
j) Fine mud particles suspended in water	Sedimentation and decantation (or) Filtration using filter paper

Question 2.
Write the steps you would use for making tea. Use the words given below and write the steps for making tea. (AS 7)

Answer:

• Take a cup of milk (solvent) in a tea kettle.
• Add one table spoon of sugar (solute), and one table spoon of tea powder (insoluble) to the solvent.
• Heat the tea kettle on the stove.
• The sugar (solute) dissolves in the milk (solvent) and the tea powder remains undissolved.
• Now filter the solution so formed.
• The filtrate is the tea (solution).
• The residue remained in the sieve is the insoluble component of tea powder.

Question 3.
Explain the following giving examples. (AS 1)
a) Saturated solution
b) Pure substance
c) Colloid
d) Suspension
Answer:
a) Saturated solution :
When no more solute can be dissolved in the solution at a certain temperature, it is said to be a saturated solution.

In a saturated solution, equilibrium with the undissolved solute at a certain temperature.

Ex :

1. Take 50 ml of water in a cup.
2. Add one spoon of sugar to the cup and stir still it dissolves.
3. Keep on adding sugar to the water in the cup and stir till no more sugar can be dissolved.
4. The solution so formed is a saturated solution.

b) Pure substance :
A substance is pure i.e., homogeneous if the com-position doesn’t change, no matter which part of the substance we take for examination.

Ex :

1. Take a small part of pure gold biscuit as a sample.
2. The composition is found to be same throughout it.

c) Colloid :
Colloids are heterogeneous mixtures in which the particle size is too small to be seen with the naked eye, but is big enough to scatter light.
Ex : Milk, butter, cheese, cream, gel, etc.

d) Suspension :
Suspension is a heterogeneous mixture in which the solute particles didn’t dissolve and the particles are visible to naked eye.
Ex : Syrups, chalk powder mixed with water, etc.

Question 4.
Classify each of the following as a homogeneous or heterogeneous mixture. Give reasons. (AS 1)

Answer:

Homogeneous mixtures	Heterogeneous mixtures
Soda water	Soil
Air	Wood
Vinegar
Filtered tea
Reason : Components in the above mixtures are uniformly distributed and we cannot see the components separately.	Reason : Components in the above mixtures are not uniformly distributed.

Question 5.
How would you confirm that a colourless liquid given to you is pure water? (AS 1)
Answer:

• Observe the smell. We should not find any smell.
• Observe with a naked eye we should not find any suspended particles or fumes or air bubbles.
• Pass a beam of light. It should not scatter.
• The temperature should be normal.
  Then the given colourless liquid is pure water.

Question 6.
Which of the following materials fall in the category of a “pure substance”? Give reasons. (AS 1)
a) Ice
b) Milk
c) Iron
d) Hydrochloric acid
e) Calcium oxide
f) Mercury
g) Brick
h) Wood
i) Air
Answer:

• Except brick and wood remaining materials given in the list can be treated as pure substances.
• Take any small part of ice, milk, iron, hydrochloric acid, calcium oxide, mercury and air and test for their components.
• We find that the composition is same throughout them.

Question 7.
Identify the solutions among the following mixtures. (AS 1)
a) Soil
b) Sea water
c) Air
d) Coal
e) Soda water
Answer:
The solutions are : sea water, air and soda water.

Question 8.
Which of the following will show “Tyndall effect”? How can you demonstrate “Tyndall effect” in them? (AS 1, AS 3)
a) Salt solution
b) Milk
c) Copper sulphate solution
d) Starch solution
Answer:
Milk shows Tyndall effect.

Demonstration :

1. Prepare the milk, copper sulphate, salt and starch solutions in different beakers.
2. Allow a beam of light through each of them.
3. The path of the light beam is clearly visible to us through milk.
4. The path of the light beam is not visible through remaining.
5. This experiment will be effective if it is performed in a dark room.

Question 9.
Classify the following into elements, compounds and mixtures. (AS 1)
a) Sodium
b) Soil
c) Sugar solution
d) Silver
e) Calcium carbonate
f) Tin
g) Silicon
h) Coal
i) Air
j) Soap
k) Methane
l) Carbondioxide
m) Blood
Answer:

Elements	Compounds	Mixtures
Sodium	Calcium carbonate	Soil
Silver	Coal	Sugar solution
Tin	Methane	Air
Silicon	Carbondioxide Soap	Blood

Question 10.
Classify the following substances in the below given table. (AS 1)

Answer:

Solution	Suspension	Colloidal dispersion
Soda water	Ink	Fog
Fruit salad	Nail polish	Aerosol sprays
Black coffee	Starch solution	Boot polish
Air Brass		Milk
		Blood
		Oil and water

Question 11.
Take a solution, a suspension, a colloidal dispersion in different beakers. Test whether each of these mixtures shows the Tyndall effect by focusing a light at the side of the container. (AS 3)
Answer:

• Take sugar solution (solution), starch solution (suspension) and milk solution (colloidal dispersion) in three different beakers.
• Focus a beam of light by torch or a laser beam at the side of each container and observe.
• We can see that the path of beam of light is clearly visible through all the solutions.
• Hence all the three solutions show ‘Tyndall effect”.

Question 12.
Draw the figures of arrangement of appatus for distillation and fractional distillation. What do you find the major difference in these apparatus? (AS 5)
Answer:

The main difference between these two apparatus is that a fractionating column is fitted in between the distillation flask and the condenser.

Question 13.
Determine the mass by mass percentage concentration of a 100 g salt solution which contains 20 g salt. (AS 1)
Answer:
Mass of salt = 20 g; Mass of salt solution = 100g

Question 14.
Calculate the concentration in terms of mass by volume percentage of the solution containing 2.5 g potassium chloride in 50 ml of potassium chloride (KCl) solution. (AS 1)
Answer:
Mass of potassium chloride = 2.5 g
Volume of potassium chloride solution = 50 ml

9th Class Physical Science 3rd Lesson Is Matter Pure? InText Questions and Answers

9th Class Physical Science Textbook Page No. 40

Question 1.
Can you give few more examples of this kind?
Answer:
Some more examples of homogeneous mixtures are sugar solution, lemon squash, fruit juices, syrups and tonics used in medicine, etc.

Question 2.
Can you prove this with an experiment?
Answer:

• Take some thick milk in a test tube.
• Pass a beam of light from torch or a laser light.
• We cannot observe the path of light through the solution.

Question 3.
If the solution is diluted, can the path of light be visible?
Answer:

• Take some thick milk in a test tube.
• Dilute it by adding some water.
• Now pass a beam of light from torch or a laser light.
• We cannot observe the path of light through the solution.

Question 4.
What would happen if you add a little more solute to a solvent?
Answer:
The solution becomes concentrated.

Question 5.
How do you determine the percentage of the solute present in a solution?
Answer:

• Take 100 ml of water in a beaker.
• Take 50 g. of sugar in a plate.
• Add a spoon of sugar to water and stir it tell the sugar dissolve in water.
• Go on adding sugar till you reach a situation that the sugar cannot be dissolved in water.
• Now weigh the sugar remained in the plate.
• Subtract thin weight from 50 g. The weight so obtained is dissolved in water.
• Hence the maximum amount of solute present in 100 ml of solvent is the percentage of solute (solubility).

9th Class Physical Science Textbook Page No. 44

Question 6.
Did you ever observe this phenomenon in the cinema halls?
Answer:
In cinema halls when we observe the projector while the movie is running, we can observe the phenomenon of “Tyndall effect”. We can see the beams of light in which dust particles also observed.

9th Class Physical Science Textbook Page No. 46

Question 7.
Is the mixture heterogeneous? Give reasons.
Answer:
The mixture of ammonium chloride and salt is a heterogeneous mixture. Even though these two are white in colour their particles do not mix.

Question 8.
How do we separate the salt and ammonium chloride?
Answer:
We can separate the salt and ammonium chloride by the method of sublimation.

9th Class Physical Science Textbook Page No. 49

Question 9.
Can you give any examples where we use fractional distillation technique?
Answer:
We use this technique in separating the components of crude oil i.e., petrol, naphthalene, kerosene, greese, etc.

9th Class Physical Science Textbook Page No. 38

Question 10.
How does a laundry dryer squeeze out water from wet clothes?
Answer:

• The laundry dryer contains a cylindrical vessel with holes on its walls.
• When wet clothes are dropped in it, it is rotated with high speed with the help of an electric motor.
• Due to centrifugation, the water from the clothes reaches to the walls of the cylinder and comes out through the holes.
• Hence the clothes are dried up.

9th Class Physical Science Textbook Page No. 40

Question 11.
a) “All the solutions are mixtures, but not all mixtures are solutions”. Discuss about the validity of the statement and give reasons to support your argument.
Answer:

• You take any solution like salt solution, sugar solution, air, etc. all are homogeneous mixtures.
• Consider a mixture of sand and iron fehlings. It is not homogeneous. Hence this is not a solution.

b) Usually we think of a solution as a liquid that contains either a solid, liquid or a gas dissolved in it. But, we can have solid solutions. Can you give some examples?
Answer:
Examples of solid solutions are :

1. Steel used in constructions (a homogeneous mixture of iron and carbon).
2. Brass (a homogeneous mixture of zinc and copper).

9th Class Physical Science Textbook Page No. 43

Question 12.
1) Have you ever observed carefully the syrup that you take for cough? Why do you shake it before consuming?
2) Is it a suspension or colloidal solution?
Answer:

1. The syrup used for cough will be shook before consuming because it consists some undissolved particles settled down.
2. Hence cough syrup is a suspension.

9th Class Physical Science Textbook Page No. 45

Question 13.
Is there any difference between a true solution and colloidal solution? If you find the differences, what are those differences?
Answer:
Differences between true solutions and colloidal solutions :

Question 14.
Why do we use different separation techniques for mixtures like grain and husk as well as ammonium chloride and salt though both of them are heterogeneous mixtures? What is the basis for choosing a separation technique to separate mixtures?
Answer:
The basis for choosing a separation technique to separate mixtures is the property of a component in the mixture i.e., solubility in water, evaporation, appearance, etc.

9th Class Physical Science Textbook Page No. 47

Question 15.
Is it possible to find out adulteration of kerosene in petrol with this technique?
Answer:
The adulteration of kerosene in petrol can be found by using density meter.

9th Class Physical Science Textbook Page No. 50

Question 16.
a) Arrange the gases present in air in increas you observe?
Answer:

Gas	B.P
Helium	268.93°C
Hydrogen	252.9°C
Neon	246.08°C
Nitrogen	195.8°C
Argon	185.8°C
Oxygen	183°C
Methane	164°C
Krypton	153.22°C
Xenon	108.12°C
Carbondioxide	78°C

b) Which gas forms the liquid first as the air is cooled?
Answer:
Oxygen forms the liquid first as the air is cooled.

9th Class Physical Science 3rd Lesson Is Matter Pure? Activities

Activity – 1

Question 1.
How can we separate cream from milk?
Answer:

• Take some milk in a vessel.
• Spin it with a milk churner for some time.
• After some time you observe, separation of a paste like solid out of the milk.
• The paste like solid is called cream.

Activity – 2

Question 2.
Explain a demonstration to identify homogeneous and heterogeneous mixtures.
Answer:

• Take two test tubes.
• Now add one tea spoon of salt to both the test tubes.
• Fill one test tube with water and another with kerosene and stir them.
• In the first test tube (water), the salt dissolves completely.
• This is a homogeneous mixture.
• In the second test tube (kerosene), the salt is not dissolved.
• This is a heterogeneous mixture.

Activity – 3

Question 3.
Describe an activity to prepare saturated and unsaturated solutions.
Answer:
Preparation of saturated solution :

1. When no more solute can be dissolved in the solution at a certain temperature, it is said to be a saturated solution.
2. Take 50 ml of water in an empty cup.
3. Add one spoon of sugar to the water in the cup.
4. Stir the water until it dissolves.
5. Keep on adding sugar to the cup and stir till no more sugar can be dissolved in it.
6. Thus formed solution is called saturated solution.
7. In a saturated solution, equilibrium with the undissolved solute at a certain temperature.

Preparation of unsaturated solution :

1. If the amount of solute present in a solution is less than that in the saturated solution, is called an unsaturated solution.
2. Now take the solution prepared by you into a beaker.
3. Heat that solution slowly by 5 to 6°C above the room temperature.
4. The undissolved solute dissolves.
5. Add some more sugar to this solution.
6. You notice that more sugar dissolves in it easily when it is heated.
7. Thus we prepared an unsaturated solution.

Activity – 4

Question 4.
What are the factors affecting the rate of dissolving ? How do you prove them?
Answer:
Factors affecting the rate of dissolving are :

1. Temperature of the solvent.
2. Size of the solute particles.
3. Stirring the solution.

Proof:

1. Take three glass beakers and fill each of them with 100 ml of water.
2. Add two spoons of salt to each beaker.
3. Place the first beaker undisturbed.
4. Stir the contents of the second beaker.
5. Heat gently the third beaker.
6. In all the cases, the salt dissolves but the time taken to dissolve is different.
7. When the beaker is heated, the salt dissolved quickly.
8. When we stir the contents, the salt dissolved but slower than heating.
9. When we observe the undisturbed beaker, the salt dissolves but at the slowest rate.
10. This shows that the temperature of the solvent, size of the solute particles, stirring of contents are the factors affecting the rate of dissolving.

Activity – 5

Question 5.
Describe an experiment to identify suspensions and colloids.
Answer:

• Take some chalk powder in a test tube.
• Take a few drops of milk in another test tube.
• Add water to these samples and stir with a glass rod.
• Now do the following steps and write your observations in the table given.

Step 1 :
Direct a beam of light from a torch or a laser beam on the test tubes. Observe the path of the light through the solutions.

Step 2 :
1) Leave the mixture undisturbed for some time.
2) See whether the solute settles down after some time.

Step 3 :
Filter the mixtures and observe any residue found on the filter paper.
Now read your observations :

Observations :

1. In the chalk mixture, the particles of chalk settled at the bottom of the test tube and on filtration, we can observe a residue on the filter paper.
2. Hence the chalk mixture is a suspension.
3. In the milk mixture, the particles of milk are uniformly spread throughout the mixture and no residue is found on the filter paper.
4. Hence milk mixture is a colloidal solution.

Activity – 6

Question 6.
Describe an example for the separation of mixtures by sublimation.
Describe a method of separating ammonium chloride from the mixture of ammonium chloride and common salt.
Answer:
Aim :
To separate ammonium chlo-ride from the mixture of ammonium chloride and common salt.

Materials required :
China dish, funnel, cotton, ammonium chloride, common salt and stove.

Procedure:

1. Take one table spoon of ammo-nium chloride and one table spoon of common salt and mix them.
2. Take the mixture in a China dish.
3. Take a glass funnel.
4. Plug the mouth of the funnel with cotton.
5. Invert the funnel over the dish.
6. Heat the dish on the stove and observe the walls of the funnel.

Observations :
Initially we find vapours of ammonium chloride and then solidified ammonium chloride on the walls of the funnel.

Activity – 7

Question 7.
Describe a method to separate the dye present in ink.
(or)
Describe an example for the separation of a mixture by the process of evaporation.
Answer:
Aim :
To separate the dye present in ink by the process of evaporation.

Materials required :
Beaker, watch glass, water, ink and stove.

Procedure :

1. Take a beaker and fill it to half its volume with water.
2. Keep 3, glass on the mouth of a beaker.
3. Put few drops of ink on the watch glass.
4. Heat the beaker and observe the watch glass.

Observations:

1. We observe some fumes coming from the watch glass.
2. Continue heating till you do not observe any further change on the watch glass.
3. A small residue will be remained on the watch glass.

Inference :

1. We know that ink is a mixture of a dye in water.
2. The residue remained on the watch glass is the dye present in the ink.

Lab Activity

Question 8.
Describe paper chromatography activity to observe the colours present in a marker ink.
(OR)
How can you perform chromatography activity in your laboratory.
Answer:
Aim :
Separating the components of ink using paper chromatography.

Materials required :
Beaker, rectangular shaped filter papers, black marker (non-permanent), water, pencil and cello tape.

Procedure:

1. Draw a thick line just above the bottom of the filter paper using the marker.
2. Pour some water into the beaker.
3. Hang the paper strip with help of a pencil and tape in such a way that it should just touch the surface of water.
4. Make sure that the ink line or mark does not touch the water.
5. Allow the water to move up the paper for 5 minutes and then remove the strip from water.
6. Let it dry.
7. Repeat the process with green marker, a permanent marker, etc.

Observations :

1. When black marker is used, we observe different colours like red, green, violet, black, etc. on the filter paper after drying.
2. When green marker is used, we observe yellow, blue, green colours on the filter paper.
3. When permanent marker is used, we cannot find any change in the mark.

Activity – 8

Question 9.
How do you separate water and kerosene from the mixture of kerosene and water?
Answer:
Aim :
To separate water and kerosene from the mixture of kerosene and water.

Materials required :
Kerosene, water, separating funnel, beakers.

Procedure:

1. Pour the mixture of kerosene and water in a separating funnel.
2. Let it stand undisturbed for some time, so that the layers of oil and water are formed.
3. Open the stopcock of the separating funnel and pour out the lower layer of water carefully.
4. Close the stopcock of the separating funnel as the oil reaches the stop cock.

Principle involved :
The immiscible liquids separate out into layers depending on their densities.

Activity – 9

Question 10.
Explain the method of separation of two miscible liquids by distillation.
Answer:
Aim :
To separate two miscible liquids (water and acetone) by distillation.

Materials required :
Stand, distillation flask, thermometer, condenser, beaker, acetone and water, one holed rubber cork.

Procedure:

1. Take a mixture of acetone and water in a distillation flask.
2. Fit it with a thermometer and clamp it to stand.
3. Attach the condenser of the flask on one side.
4. On the other side of the condenser keep a beaker to collect distillate.
5. Heat the mixture slowly.
6. Keep a close watch on the thermometer.
7. The acetone vapourizes and condenses in the condenser.
8. The acetone can be collected from the condenser outlet.
9. Water remains in the distillation flask.
10. The separation technique used above is called distillation.

Activity – 10

Question 11.
How do you separate copper metal from the mixture of copper sulphate and aluminium?
Answer:

• Take a concentrated solution of copper sulphate into a beaker.
• Drop an aluminium foil in the beaker.
• After some time, we observe a layer of copper deposited on the aluminium foil.
• The solution becomes colourless.
• A chemical reaction takes place among the copper ions present in the solution with aluminium and copper metal is separated.

AP State Syllabus AP Board 9th Class Social Studies Important Questions Chapter 6 Agriculture in India.

AP State Syllabus 9th Class Social Studies Important Questions 6th Lesson Agriculture in India

9th Class Social 6th Lesson Agriculture in India 1 Mark Important Questions and Answers

Question 1.
Expand MSP. (SA-II : 2016-17)
Answer:
Minimum Support Price

Question 2.
Draw sketch map of India and identify paddy cultivating state. (SA-II : 2016-17)
Asnwer:

Question 3.
Why is a MSP needed? (SA-II : 2017-18)
Answer:
The government sets the MSP so as to cover the cost of cultivation and allow a little bit of profit to the farmer.

Question 4.

Study the map and answer the following question. (SA-I : 2018-19)
What is major crop in the shaded areas of the map?
Answer:
Paddy.

Question 5.
Name any two cropping seasons in India? (SA-I : 2018-19)
Answer:
Kharif, Rabi, Zaid are the three cropping seasons.

9th Class Social 6th Lesson Agriculture in India 2 Marks Important Questions and Answers

Question 1.
At present we are using under ground water heavily and they reached an endangered stage, indicate measures to restore the ground water. (SA-III : 2015-16)
Answer:
The following steps are the measures to restore ground water.

• Vegetation like trees and grasses and bonds are used to enhance ground water.
• We follow watershed development projects.
• Rainwater harvesting should be practiced.
• Reduce the wastage of water.

Question 2.
Observe the Bar graphs and write your observations. (SA-II : 2016-17)

Answer:

• Above Bar graph tells us how many cultivators and how many agricultural labourers are there in India.
• Years are passing away gradually percentage of cultivators is decreasing and the persons, who are agricultural labourers are increasing

Question 3.
Show the below information on a bar graph and based on this, write your observation. (SA-III : 2016-17)

Year	Production of food grains in million tones
1980-81	130
1990-91	176
2000-01	197
2010-11	242

Answer:

The above graph explains production of food grains is gradually increased from 1980-81 to 2010-11. The main reason is we are following green revolution methods in our agricultural iands.

Question 4.
Today food materials constitute only about three percent of Indian Imports. Explain the role of Green Revolution that lies behind this achievement. (SA-III : 2016-17)
Answer:
The production of food grains has increased five times over last five decades from 51 to 242 million tonnes.

The green revolution helped farmers to produce higher level of foodgrains and non- foodgrains on the same plot of land they had. There was no major increase in the land used for cultivation.

In 1960s a farmer was able to produce on an average only 287 kilograms of foodgrains be it paddy or wheat on one acre of cultivable land. Today the same farmer is able to produce nearly 800 kilograms of foodgrains per acre of cultivable land.

Importance of Green Revolution :

1. Using of highyielding varieties of seeds.
2. Using of pesticides and insecticides.
3. Providing better water management resources.

Question 5.
Write the names of cropping seasons in India and write the tenure of season. (SA-II : 2017-18)
There are three cropping seasons.

Crop	Tenure
1. Kharif	Mid June to October
2. Rabi	November to March
3. Zaid	April, May, Mid June

9th Class Social 6th Lesson Agriculture in India 4 Marks Important Questions and Answers

Question 1.
“The green revolution has resulted in a loss of soil fertility and ever increasing costs to farmers”. Do you agree with this statement? Explain. (SA-I : 2018-19)
(OR)
“The green revolution has actually resulted in a loss of soil fertility and ever increasing cost to the farmers’ (SA-II : 2018-19)
Do you agree with the above statement? Provides reasons to support your answer.
Answer:
Yes, I agree with the above statement by following reasons.

1. In Green Revolution, the farmers are encouraged to pump ground water to water intensive crops in low rainfall areas.
2. This unsustainable pumping has reduced water storage in ground.
3. Consequently, many wells and tube wells have run dry.
4. More over the use of chemical fertilizers has also affected the long term fertility of the soil. Due to this cost of production is increasing to farmers.
5. Hence we can say that Green Revolution has short-term gains and long term losses.
6. Production of food grains (in million tonnes)

Question 2.

Observe the above graph and answer the following questions.
1. What does the graph given above denotes? (SA-III : 2015-16)
Answer:
The above graph explains the production of foodgrains from 1950-51 to 2010-11 years.

2. When compared to 1970-71, how many million tonnes of food grains are produced more in 2010-11? (SA-III : 2015-16)
Answer:
Compare with 1970-71 to 2010-11 the food grain production is increased from 108 million tonnes to 242 million tonnes, it means ⇔ 134 million tonnes production is more.

3. In which decade was the production of food grains more? (SA-III : 2015-16)
Answer:
From 1981 to 1990 in the middle of the years means, in this decade the production of food grains is more.

4. What are the reasons for the increase in production of food grains? (SA-III : 2015-16)
Answer:
The main reason is use of Green Revolution methods.

5. What is the overall trend of food grain production depicted in the graph? (SA-I : 2019-20)
Answer:
Food grain production is increasing.

6. What could be the possible reason for this trend? (SA-I : 2019-20)
Answer:
Because of Green Revolution.

Question 3.
“Conserving rainfall that the area receives is the first step. There are several ways that people can stop rainwater from quickly running off so that it can soak into the ground, and recharge the groundwater”.
Q : Comment on watershed development programms being implemented in dry land area. (SA-II : 2016-17)
Answer:
Unlike the cultivation of HYVs in irrigated lands, dryland farming possess different challenges.

1. Conserving rainfall that the area receives is the first step.
2. There are several ways that people can stop rain water from quickly running off, so that it can soak into the ground, and recharge the ground water.

This is done through Watershed Development Programmes which include afforestation, bunding, building check dams and tanks.

Not send any chemical waste into underground.

Try to reduce the wastage of daily use water.

Create awareness among the all people about the importance of underground water and its recharge.

Question 4.
Food security of a nation depends on agricultural sector. Explain about agricultural sector in India. (SA-III : 2016-17)
Answer:
The food security of a nation depends on agriculture and this sector ensures food security to the nation.

Importance of agriculture :

• A variety of raw materials required for industries are cultivated on farms.
• Agriculture is a major source of livelihood for millions – giving employment to a large section of people.
• More than half the proportion of workers in India is working in agriculture and its related activities.
• 70% of working women are engaged in agriculture.
• Due to green revolution, India became self sufficient in food grains.
• Due to rise in food grains production, it was no longer necessary to import food grains from other countries.

Question 5.
Study the graph and answer the questions given below. (SA-II : 2018-19)

1. What is the difference between agriculture labourers and cultivators?
2. In 1971, what was the percentage of cultivators?
3. Suggest other alternative job opportunities for landless agriculture labourers,
4. In which year the highest percentage of cultivators was recorded?
Answer:
1. Cultivator means:
Cultivators are those who have, some land and also use land belongs to other for cultivation.

Agricultural labourers :
Agriculture labourers are those who are landless labourers who work on other lands.

2. 62%

3. Other alternative works.

1. rearing of animals
2. selling of vegetables
3. work in brick kiln.

4. 1961

Question 6.
What suggestions do you recommend to solve the problems associated with current Indian agriculture sector? (SA-I : 2018-19)
Answer:
Suggestions :
1. Better irrigation facilities :
Indian agriculture is mainly dependent on monsoon. So permanent means of irrigation should be developed.
Ex: Tube wells & Canals.

2. Supply of Quality seeds :

1. Quality seeds should be sold through co-operative societies or village panchayats.
2. Marginal farmers should be given seeds on loan.

3. Green Manure :
Farmers should be educated for firing green manure. Oil cakes may be used as fertilizers.

4. Credit Facilitied :

1. Farmers should be advanced loans at reasonable rates of interest.
2. Regional Rural Banks should be opened.

5. Agricultural Marketing:
Agricultural marketing should be improved so that the farmer gets proper price for their produce ware housing facilities should be improved. Means of transport should be strengthened.

6. Time to time weather reports telecast by govt through media.

Question 7.
Observe the table and answer the questions given below. (SA-I : 2018-19)
Number of farmers and land they possess in India (2010 – 2011)

1. Who are considered as large farmers as per the above table?
2. Which type of farmers are high in number?
3. How many total acres of land do the farmers cultivate in India?
4. How much of land on an average does each marginal farmer cultivate?
Answer:

1. The farmers who have more than 25 acres of land and they cultivated that land are called as large farmers.
2. Number of marginal farmers are more.
3. 3932 lakhs acres of land cultivated by Indian farmers.
4. 0.95 acres of land is cultivated by marginal farmers.

Question 8.
Write some methods through which the problem of falling ground water levels can be salved. (SA-I : 2019-20)
Answer:
The problem of falling ground water levels can be solved through these methods.

1. Construction of check dams.
2. By Maintaining small percolation tanks in fields.
3. Soaking pits.
4. By providing bunds and catch drains.
5. Plantation of trees in open fields.
6. Encouragement to grow forests.
7. Should ban felling trees.
8. Recycle and reuse of ground water.

9th Class Social 6th Lesson Agriculture in India Important Questions and Answers

Question 1.
Name one staple crop of India and the regions where it is produced.
Answer:
Rice:

1. Rice is the staple food crop of a majority of the people in India.
2. India is the second largest producer of rice in the world.
3. Rice is grown in the plains of north and north-eastern India, coastal areas and the deltaic regions.
4. Canal irrigation and tubewells have made it possible to grow rice in areas of less rainfall such as Punjab, Haryana and western Uttar Pradesh and parts of Rajasthan.

Question 2.
How many cropping seasons are there? What are they?
Answer:
India has three cropping seasons. They are –

1. Rabi
2. Kharif
3. Zaid

Question 3.
Name some important crops of India, states which produce them and reasons both and natural and other factors contributed to their growth.
Answer:

Question 4.
What is the fertility of the soil?
Answer:

• The soil is said to be fertile if it has the right amounts of mineral particles as well as organic components.
• Then only the soil can provide the roots of plants with right amounts of water, minerals and air.

Question 5.
How is organic farming different from traditional farming?
Answer:

• We use organic material in organic farming whereas we use natural manure in traditional farming.
• We use HYV seeds and key elements of new agricultural technologies in organic farming.
• Organic farming gives high productivity in short duration whereas in traditional farming we experience less productivity and long duration of crop.

Question 6.
Why is agriculture important to Indian economy?
Answer:

• The food security of a nation depends on agriculture.
• A variety of raw materials required for industries are cultivated on farms.
• Agriculture is a major source of livelihood for millions of people in our country.
• More than half the proportion of workers in India is working in agriculture and its related activities.
• Nearly 70% of the working women are engaged in agriculture.

Hence agriculture is important to Indian economy.

Question 7.
How many kinds of people are engaged in agriculture? Name them.
Answer:
Two kinds of people are engaged in farming. They are :

1. Agricultural labourers
2. Cultivators.

Question 8.
Distinguish between cultivators and agricultural labourers.
Answer:

Cultivators	Agricultural labourers
1. Cultivators are those who have some land and also use land belongs to others for cultivation.	1. Agriculture labourers are those who are landless labourers who work on others’ lands.
2. Cultivators are self employed.	2. Whereas agricultural labourers have to depended on working on others’ fields for livelihood.

Question 9.
How many varieties of crops are grown in India? What are they?
Answer:
A variety of crops are cultivated by farmers in India. They are broadly categorised into two :

1. Food crops
2. Non-food crops.

Question 10.
Give examples of food grains and non-food grains.
Answer:

• Food grains include cereals such as rice, wheat, jowar, bajra, maize, ragi, barley, and small millets and pulses-gram, red gram, and other pulses.
• Non-food grains include oilseeds such as groundnut, sesame, rapeseed and mustard, linseed, castor seed, and sunflower, etc.

Question 11.
What is Green Revolution? What are the effects of Green Revolution?
Answer:

• The policy introduced by Government with regard to the agricultural sector is known as Green Revolutin.
• It refers to the specific plant improvement notably to the development of high yielding varieties for the increase of crop production.

Effects of Green Revolution:

1. The spread of HYVs to large parts of the country has led to a significant increase in crop production in the country.
2. So, it was no longer necessary to import food grains from other countries.
3. The procurement of food grains by FCI could be used in case of shortage and can avoid drought or famine like situations and also used to supply food grains to inaccessible areas.
4. In 1960, a farmer was able to produce on an average of 287 kgs of foodgrains, today the same farmer is able to produce nearly 800 kgs of food grains per acre.
5. The Green Revolution has brought in several environmental imbalances.

Question 12.
Name some of the states of India where “slash and burning” farming is practised.
Answer:
Punjab, Haryana, Odisha, Karnataka, Telangana, Andhra Pradesh, Madhya Pradesh, Uttar Pradesh, and some parts of Rajasthan.

Question 13.
What is the fertility of the soil?
Answer:

1. The soil is said to be fertile if it has the right amounts of mineral particles as well as organic components.
2. Then only the soil can provide the roots of plants with right amounts of water, minerals, and air.

Question 14.
How many kinds of people are engaged in agriculture? Name them.
Answer:
Two kinds of people are engaged in farming. They are :

1. Agricultural labourers
2. Cultivators.

Question 15.
What is Green Revolution?
Answer:
The policy introduced by Government with regard to the agricultural sector is known as Green Revolution.

Question 16.
Compare and contrast simple subsistence farming and intensive subsistence farming.
Answer:

Simple subsistence farming	Intensive Substitence farming
1. Agriculture is practiced in small patches of land.	1. Practised in the areas of high population density.
2. Primitive tools like hoe, dao and digging sticks are used.	2. No primitive tools are used but mechanised tools.
3. Family or community labour is the source of labour.	3. It is labour intensive farming.
4. Natural fertility of the soil, monsoon etc. are important.	4. High doses of biochemical inputs are used.
5. It is a ‘slash and burn1 agriculture.	5. Irrigation is used to obtain higher production.

Question 17.
What do you know about Zaid cropping season?
Answer:

• In between the Rabi and Kharif seasons there is a short season.
• It includes summer months and is known as Zaid season.
• Crops grown during this season are like watermelon, muskmelon, cucumber, vegetables and fodder crops.

Question 18.
Read the following and answer the questions given below.

Why does Government buys and stores some grain? A lot of grain comes into the market at harvest time. One problem farmers faced was the low price of grain during this time. This means farmers were not able to sell grain at a high enough price to be able to repay their loans and continue using the new farming methods. They need to be protected from traders who might try to purchase the grains at low prices. Therefore, the government decided to set a Minimum Support Price (MSP). A Mini¬mum Support Price is a price at which the farmers can sell their grain, if they want, to the government. The government sets the MSP so as to cover the cost of cultivation and allow a little bit of profit to the farmer. Because of the MSP, farmers are not forced to sell their grains at cheaper prices to the traders. The Food Corporation of India (FCI) was formed by the government to purchase food grains from the farmers and store them. It keeps stockpiles and supplies grain to ration shops and other government schemes (e.g. for midday meals in schools).

1. What problem do farmers face during harvest season?
Answer:
The farmers face the problem of the low price of grain during harvest season.

2. How can the farmers be protected from the low prices of grains?
Answer:
The government protects the farmers by setting a Minimum Support Price (MSP).

3. What is Minimum Support Price?
Answer:
The MSP is a price at which the farmers can sell their grain, if they want, to the government.

4. How does the MSP protect the farmer?
Answer:
The government sets the MSP so as to cover the cost of cultivation and allow a little bit of profit to the farmer.

5. What is the organization that purchases food grains from the farmers?
Answer:
The Food Corporation India purchases food grains from the farmers.

Question 19.
Observe the following information and answer the questions given below.

Cropping seasons	Period	Crops grown
Kharif	They are grown with the onset of monsoons, harvested in September to October.	Paddy, maize, jower, bajra, red gram, green gram, black gram, cotton, jute, groundnut, etc.
Rabi	They are sown in winter from October – December and harvested in summer.	Wheat, barley, peas, gram and mustard.
Zaid	In between Rabi and Kharif there is a short period during summer months known as the zaid season.	Watermelon, muskmelon, cucumber, vegetables and fodder crops.

1. How many cropping seasons are there?
Answer:
There are three cropping seasons.

2. Name different cropping seasons.
Answer:
Kharif, Rabi and Zaid are different cropping seasons.

3. When do we have Rabi season?
Answer:
Rabi crops are sown in winter from October to December and harvested in summer.

4. Name the crops that are grown in Kharif season.
Answer:
Paddy, maize, jower, bajra, red gram, cotton, jute, groundnut etc., are grown in Kharif season.

5. Name the crops that are grown in Zaid season.
Answer:
Watermelon, muskmelon, cucumber, vegetables are grown in Zaid season.

Question 20.
Complete the data in the table:
Number of farmers and land they possess in India (2010-2011)

A) Percentage of different category of farmers :
1. How much percentage of Marginal farmers are there.
Answer:
67 %

2. How much percentage of small farmers are there?
Answwr:
18 %

3. How much percentage of large farmers are there?
Answer:
0.7 %

B) How much land they operate with?
1) Marginal farmers hold _________ of land.
2) Small farmers hold _________ of land.
3) Semi-medium farmers hold _________ of land.
4) Medium farmers hold _________ of land.
5) Large farmers hold _________ of land.
Answer:

1. 22%
2. 22%
3. 24%
4. 21%
5. 11%

C) Average amount of land operated by farmers :
1) Average amount of land possessed by marginal farmers is _________ acres.
2) Small farmers hold _________ acres of land.
3) Average amount of land possessed by large farmers is _________ acres.
4) Average land holding in India is _________ acres.
Answer:

1. 0.94
2. 3.51
3. 42.9
4. 13.65

Question 21.
What are the long run uses of chemical fertilizers and pesticides?
Answer:

• The chemical fertilizers are basically made from petro chemicals and therefore derived from petroleum.
• These fertilizers remain in the soil and also mix with water.
• This results in the contamination of soil and water.
• As a result many micro organisms like earthworms are destroyed. This in turn affects the long term fertility of the soil.

Question 22.
In which areas were the new methods of agriculture first tried?
Answer:
The new methods were initially implemented in Punjab, Haryana, western Uttar Pradesh, and in some districts of Telangana, Andhra Pradesh, and Tamilnadu.

Question 23.
How were farmers able to raise higher amount of food grains on the same plot of land over the years?
Answer:
The use of High Yielding Varieties of seeds, chemical fertilizers, machinery, etc. made the farmers to raise higher amount of food grains on the same plot of land over the years.

Question 24.
Why did the Indian government not allow farmers to export foodgrains during the Green Revolution?
Answer:
There would be a shortage of food grains if the government allows farmers to export food grains. So the government did not allow farmers to export food grains.

Question 25.
How did the partition of the country in 1947 affect the jute industry?
Answer:
We have lost the major jute growing areas during partition. Hence the jute industry was badly affected.

Question 26.
In your opinion what would be the minimum amount of land required to do viable farming?
Answer:
The minimum amount of land required to do viable farming maybe 2 acres for viable farming.

Question 27.
Why do only a small section of farmers have a powerful voice?
Answer:
Percentage of large and medium farmers is 5% but they hold 32% of total cultivable land. Their average landholding is also high. Hence they have a powerful voice.

Question 28.
Assess the role of monsoons in Indian agriculture nowadays?
Answer:

• Indian agriculture has always been dependent on monsoons.
• Arrival and impact of monsoon decides the fate of agriculture.
• It is both uncertain and irregular.
• The large scale irrigation serves only one third of crop area.
• The remaining has to suffer the vagaries of the monsoon.
• Thus one can term Indian agriculture as ‘a gamble with monsoons.’

Question 29.
How can you say that now India is practising subsistence farming?
Answer:

• India is a densely populated country.
• Farmers here are force to use small land holdings.
• Most farmers produce enough for their own consumption.
• They try to obtain maximum yield from available lands.
• They are artificial irrigation and manure etc.
• This type of farming is known as intensive subsistence farming.
• Thus we can say India is practising subsistence farming.

Question 30.
Do you feel that the farmers who cultivate are happy? If not, what are the reasons? What are the factors that affect agriculture?
Answer:
I feel that the farmers who cultivate are not happy.
Reasons:

1. They are not able to earn according to their labour.
2. They lost their confidence.
3. Nature is also not co-operating with them.

Factors that affect agriculture :

1. Low fertile soils
2. Improper usage of pesticides
3. Small land holdings
4. Unpredictable monsoons
5. Outdated agricultural methods
6. Improper market facilities, etc.

Question 31.
Locate the following on India Map.
Paddy, wheat and maize growing areas.

Answer:
Paddy – West Bengal, Odisha, Telangana, Andhra Pradesh and coastal areas.
Wheat – Punjab, Haryana, Uttar Pradesh
Maize – Karnataka, Telangana, Andhra Pradesh, Maharashtra and Bihar.

Question 32.
Locate the following on India map.
Pulses, sugarcane, cotton growing areas.

Answer:
Pulses – Madhya Pradesh, Maharashtra, Uttar Pradesh, Telangana and Andhra Pradesh.
Cotton – Gujarat, Maharashtra.
Sugarcane – Uttar Pradesh, Maharashtra, Telangana, Andhra Pradesh, Tamilnadu.

Question 32.
Locate the following rivers on the outline map of India.
1) Narmada
2) Tapati
3) Godavari
4) Krishna
5) Cauvery
6) Mahanadi
7) Indus
8) Ganga
Answer:

Question 33.
State your opinion on the new agricultural technologies such as Green Revolution.
Answer:

• Yes, we agree that government has taken initiative in increasing the production of different crops.
• But introduction of HYVs has created some economical imbalances.
• They need plenty of water which may reduce the water levels and at one stage we would face scarcity of water.

Question 34.
State your opinion on free power supply to farmers and the problems that are faced by marginal farmers due to free power supply.
Answer:

• Free power supply to a section of farmers has encouraged them to pump groundwater.
• Consequently, many wells and tubewells have run dry.
• This has pushed the marginal and small farmers out of cultivation.

Question 35.
How did the partition of the country in 1947 affect the Jute industry?
Answer:
We have lost the major jute growing areas during partition. Hence the jute industry was badly affected.

Question 36.
What measures would you suggest to protect agriculture from intense commercial farming?
Answer:

• To protect agriculture from intense commercial farming, we should shun the use of High Yielding Varieties of Seeds.
• Then we can limit the usage of water.
• Then we can limit the usage of chemical fertilisers and pesticides.
• We can save the produce for seeds.
• We can adopt organic farming, which requires very low input costs.
• Organic farm produce also serves health better.

Question 37.
What measures would you suggest for the cultivation of cotton crop?
Answer:

• Cotton grows well in drier parts of the black cotton soil of the Deccan Plateau.
• It requires high temperature, light rainfall or irrigation.
• It needs 210 frost free days and bright sunshine for its growth.
• It requires 6 to 8 months to mature.

AP State Syllabus AP Board 9th Class Physical Science Solutions Chapter 4 Atoms and Molecules Textbook Questions and Answers.

AP State Syllabus 9th Class Physical Science Solutions 4th Lesson Atoms and Molecules

9th Class Physical Science 4th Lesson Atoms and Molecules Textbook Questions and Answers

Improve Your Learning

Question 1.
Draw the diagram to show the experimental setup for the law of conservation of mass. (AS 5)
(OR)
Draw the experimental arrangement used in verifying law of conservation of mass. Write the law of conservation of mass.
Answer:

Question 2.
Explain the process and precautions in verifying law of conservation of mass. (AS 5)
(OR)
Explain the procedure to prove in a chemical reaction the mass neither destroyed.

Answer:
Aim :
To verify law of conservation of mass.

Material required :
Sodium sulphate,Barium chloride, distilled water, conical flask, spring balance, small test tube, rubber cork, thread, retort stand.

Procedure:

1. Prepare a solution of sodium sulphate by dissolving approximately 2 gm of sodium sulphate in 100 ml distilled water in a 250 ml conical flask.
2. Prepare a Barium chloride solution by dissolving approximately 2 gm of potassium iodide in 100 ml water in another conical flask.
3. Take 100 ml solution of sodium sulphate in 250 ml conical flask.
4. Also take 4 ml solution of Barium chloride in test tube.
5. Hang the test tube in the flask carefully without mixing the solutions. Put a cork on the flask.
6. Weigh the flask with its contents carefully by spring balance.
7. Now tilt and swirl the flask, so that the two solutions mix.
8. Weigh the flask again by the spring balance.

Observations:

1. Weight of flask and contents before mixing = m₁ g
2. Weight of flask and contents after mixing = m₂ g

Conclusion :

1. We have observed that the two weights i.e., mj and m2 are equal.
2. This proves the law of conservation of mass.

Precautions:

1. Care should be taken while handling chemicals.
2. Glass apparatus may slip and break down. Hence make sure that they should not slip from your hands.
3. Contents of the conical, ffhsk should not mix before weighing first time.
4. Tie a thick thread to the conical flask, so that it will not slip while weighing.

Question 3.
15.9g of copper sulphate and 10.6g of sodium carbonate react together to give 14.2g of sodium sulphate and 12.3 g of copper carbonate. Which law of chemical combination is obeyed? How? (AS 1, AS 2)
Answer:
Reactants:
Mass of copper sulphate = 15.9 g ; Mass of sodium carbonate = 10.6 g
Total mass of reactants = 15.9 + 10.6 = 26.5 g

Products:
Mass of sodium sulphate = 14.2 g ; Mass of copper carbonate = 12.3 g
Total mass of products = 14.2 + 12.3 = 26.5 g
∴ Total mass of reactants is equal to total mass of products. This is the “Law of conservation of Mass”.

Question 4.
Carbon dioxide is added to 112 g of calcium oxide. The product formed is 200 g of calcium carbonate. Calculate the mass of carbon dioxide used. Which law of chemical combination will govern your answer? (AS 1, AS 2)
Answer:

1. Let x g of carbon dioxide is added to 112 g of calcium oxide.
2. The product is 200 g of calcium carbonate.
3. According to law of conservation of mass, ,
   Total mass of reactants = Total mass of products
   x+ 112 = 200 g
   x = 88 g
   ∴ 88 g of carbon dioxide is used.

Question 5.
0.24 g sample of compound of oxygen and boron was found by analysis to contain 0.144 g of oxygen and 0.096 g of boron. Calculate the percentage composition of the compound by weight. (AS 1)
Mass of compound of oxygen and boron = 0.24 g
On analysis,
Mass of oxygen in the compound = 1.44 g
Mass of boron in the compound = 0.096 g

Question 6.
In a class, a teacher asked students to write the molecular formula of oxygen. Shamita wrote the formula as 02 and Priyanka as O. Which one is correct? State the reason. (AS 1, AS 2)
Answer:
Shamitha’s answer is correct.
Reason :

1. Oxygen is diatomic.
2. Two atoms of oxygen combine to form oxygen molecule.
3. Hence the formula of oxygen molecule will be ‘O₂‘.

Question 7.
Imagine what would happen if we do not have standard symbols for elements. (AS 2)
(OR)
Is it necessary to use symbols for elements? Write your opinion.
Answer:

• Chemistry involves a lot of reactions.
• If we do not have symbols, we have to write their names to represent the reactions.
• This is very tedious work.
• To avoid this, we need standard symbols to elements, which are universally accepted.
• In advanced studies, balancing of equations, atoms present in a compound, etc. will not be understood without symbols.
• Simply chemistry will not be developed unless symbols, formulae, etc. are not known.

Question 8.
Mohith said “H₂ differs from 2H.” Justify. (AS 1)
Answer:
H₂ is the hydrogen molecule in which two hydrogen atoms are combined to form one hydrogen molecule.

2H is the hydrogen atom. Here 2 hydrogen atoms are ready to participate in chemical reaction.

Question 9.
Lakshmi gives a statement “CO and Co both represent element”. Is it correct? State reason. (AS 1, AS 2)
Answer:
Lakshmi’s statement is incorrect.

Reason :

1. CO stands for carbon monoxide, a compound, which consists carbon and oxygen atoms.
2. This can be identified with the help of both C and O are capital (upper case) letters.
3. Co stands for cobalt, an element.
4. This can be identified with the help of ‘C’ is capital (upper case) letter and ‘o’ small (lower case) letter.

Question 10.
The formula of water molecule is H₂O. What information do you get from this formula? (AS 1)
Answer:

• Water is a combination of hydrogen and oxygen.
• Two hydrogen atoms and one oxygen atom combine to form one water molecule.
• Molecular weight of water molecule is 18. [Hydrogen 1, Oxygen 16. H₂O ⇒ 2 × 1 + 16=18]
• 18 g of water molecule contains 6.022 × 10²³ particles in it.
• Valency of hydrogen is 1 and oxygen is 2.

Question 11.
How would you write 2 molecules of Oxygen and 5 molecules of Nitrogen? (AS 1)
Answer:
2 molecules of oxygen → 2O₂
Reason :

1. Oxygen is diatomic element.
2. Two oxygen atoms combine to form one oxygen molecule.
3. The formula of oxygen molecule is O₂.

5 molecules of nitrogen → 5N₂
Reason :

1. Nitrogen is also diatomic element.
2. Two nitrogen atoms combine to form one nitrogen molecule.
3. Molecular formula of nitrogen is N₂.

Question 12.
The formula of a metal oxide is MO. Then write the formula of its chloride. (AS 1)
Answer:

• The valency of oxide is 2 i.e., O^-2.
• The formula of a metal oxide is given as MO.
• Hence the valency of the given metal must be 2 i.e., M⁺².
• Valency of chloride is 1 i.e., C^–.
• Therefore according to criss-cross method, the formula of given metal chloride will be MCl₂.

Question 13.
Formula of calcium hydroxide is Ca(OH)₂ and zinc phosphate is Zn₃(PO₄)₂. Then write the formula to calcium phosphate. (AS 1)
(OR)
Formula of calcium hydroxide is Ca(OH)₂ and zinc phosphate is Zn₃(PO₄)₂. Then write the valencies of calcium and phosphate and then write the formula of calcium phosphate.
Answer:

• Formula of calcium hydroxide is Ca(OH)₂.
• From criss-cross method we know that the valency of calcium is 2 i.e., Ca⁺² and hydroxide is 1 i.e., OH^–.
• Formula of zinc phosphate is Zn₃(PO₄)₂.
• Valency of Zn is 2 i.e., Zn^+2, and valency of phosphate is 3 i.e., PO₄^-3.
• Now the formula of calcium phosphate according to criss-cross method is Ca₃(PO₄)₂.

Question 14.
Find out the chemical names and formulae for the following common household substances. (AS 1)
a) Common salt
b) Baking soda
c) Washing soda
d) Vinegar
Answer:

Common household substance	Chemical name	Formula
a) Common salt	Sodium chloride	NaCl
b) Baking soda	Sodium bicarbonate	NaHCO3
c) Washing soda	Sodium carbonate	Na2CO3
d) Vinegar	Impure dilute acetic acid	CH3COOH

Question 15.
Calculate the mass of the following. (AS 1)
a) 0.5 mole of N₂ gas
b) 0.5 mole of N atoms
c) 3.011 × 10²³ number of N atoms
d) 6.022 × 10²³ number of N₂ molecules
Answer:
a) 0.5 mole of N₂ gas :
Mass of one mole of N₂ gas = 28 g. (∵ Molecular wt. of N₂ = 28)
Mass of 0.5 mole of N₂ gas = 28 × 0.5 = 14 g

b) 0.5 mole of N atoms :
Mass of one mole of N atoms = 14 g (∵ Atomic wt. of N = 14)
Mass of 0.5 mole of N atoms = 14 × 0.5 = 7 g

c) 3.011 × 10²³ number of N atoms :
Mass of 6.022 × 10²³ number of N atoms = 14 g

d) 6.022 × 10²³ number of N₂ molecules :
Mass of 6.022 × 10²³ number of N₂ molecules = 28 g

Question 16.
Calculate the number of particles in each of the following. (AS 1)
a) 46 g of Na
b) 8 g of O₂
c) 0.1 mole of hydrogen
Answer:
a) 46 g of Na :
Atomic weight of Na = 23
Number of particles in 23 g of Na atom = 6.022 × 10²³

b) 8 g of O₂ :
Molecular weight of O₂ is 32.
Number of particles in 32 g of O₂ molecule = 6.022 × 10²³

c) 0.1 mole of hydrogen :
Atomic weight of hydrogen is 1.
Number of particles in 1 mole of hydrogen = 6.022 × 10²³
Number of particles in 0.1 mole of hydrogen= \(\frac{0.1}{1}\) × 6.022 × 10²³ = 6.022 × 10²²

Question 17.
Convert into moles. (AS 1)
a) 12 g of O₂ gas
b) 20 g of water
c) 22 g of carbon dioxide
Answer:
a) 12 g of O₂ gas :
Molecular weight of O₂ is 32.
∴ Number of moles of 32 g of O₂ gas = 1

b) 20 g of water :
Molecular weight of water (H₂O) is 18.
Number of moles of 18 g of water = 1
Number of moles of 20 g of water = \(\frac{20}{18}\) x 1 =1.11

c) 22 g of carbon dioxide :
Molecular weight of carbon dioxide (CO₂) is 44.
∴ Number of moles of 44 g of CO₂ = 1

Question 18.
Write the valencies of Fe in FeCl₂ and FeCl₃. (AS 1)
Answer:

1. In FeCl₂, the valency of Fe is 2.
2. In FeCl₃, the valency of Fe is 3.

Question 19.
Calculate the molar mass of sulphuric acid (H₂SO₄) and glucose (C₆H₁₂O₆). (AS 1)
Answer:
a) Formula of sulphuric acid is H₂SO₄.
Molecular mass of H₂SO₄ = 2 × 1 + 1 × 32 + 4 × 16 = 2 + 32 + 64 = 98 u
∴ Molar mass of H₂SO₄ = 98 g

b) Formula of glucose is C₆H₁₂O₆.
Molecular mass of C₆H₁₂O₆ = (6 × 12) + (12 × 1) + (6 × 16) = 72 + 12 + 96 = 180 u
∴ Molar mass of C₆H₁₂O₆ = 180 g.

Question 20.
Which has more number of atoms – 100 g of sodium or 100 g of iron? Justify your answer. (Atomic mass of sodium = 23 u, atomic mass of iron = 56 u) (AS 1)
Answer:
100g of sodium has more number of atoms than 100g of iron.

Justification :
1) Atomic mass of sodium = 23 u
23 g of sodium contains 6.022 × 10²³ atoms.
100 g of sodium contains = \(\frac{100}{23}\) × 6.022 × 10²³ = 26.1826 × 10²³ atoms of sodium.

2) Atomic mass of iron = 56 u
∴ 56 g of iron contains 6.022 × 10²³ atoms.
100 g of iron contains = \(\frac{100}{56}\) × 6.022 × 10²³ = 10.7535 × 10²³ atoms of iron.

Question 21.
Complete the following table. (AS 1)

Answer:

Question 22.
Fill the following table. (AS 1)

Answer:

Question 23.
Make placards with symbols and valencies of the atoms of the elements separately. Each student should hold two placards, one with the symbol in the right hand and the other with the valency in the left hand. Keeping the symbols in place, students should criss-cross their valencies to form the formula of a compound.
Answer:
Student’s activity.

Question 24.
Take empty blister packs of medicines. Cut them into pieces having

Hence the formula of sodium carbonate will be Na₂ CO₃
Hence the forrnu A. Student’s activity.

9th Class Physical Science 4th Lesson Atoms and Molecules InText Questions and Answers

9th Class Physical Science Textbook Page No. 56

Question 1.
Does the weight of iron rod increase or decrease, on rusting?
Answer:
The weight of iron rod decreases on rusting.

Question 2.
Where does the matter charcoal go?
Answer:
The charcoal, on burning, gives off CO₂ which is mixed in atmosphere. The residue is remained as ash.

Question 3.
Wet clothes dry after some time – where does the water go?
Answer:
Water evaporates and mixed in the atmosphere.

Question 4.
What happens to magnesium on burning it in air?
Answer:
Magnesium on burning in air gives a bright light and ash is remained. The ash is magnesium oxide.

Question 5.
What happens to sulphur on burning it in air?
Answer:
Sulphur on burning, changes its state and colour.

9th Class Physical Science Textbook Page No. 57

Question 6.
Did you observe any precipitate in the reaction?
Answer:
In the flask, a reaction takes place between lead nitrate and potassium iodide.

Question 7.
Do you think that a chemical reaction has taken place in the flask? Give reason.
Answer:
Yes, the contents in the flask are changed as lead iodide and potassium nitrate.

9th Class Physical Science Textbook Page No. 58

Question 8.
Do the weights of the flask and its contents change during the activity?
Answer:
The weights of the flask and its contents do not change before and after reaction.

Question 9.
What are your conclusions?
Answer:
Mass was neither created nor destroyed.

Question 10.
What do you observe from table – 1?
Answer:
The components of a compound are mixed at same proportions in any sample.

9th Class Physical Science Textbook Page No. 59

Question 11.
What difference do you observe in percentage of copper, carbon, and oxygen in two samples?
Answer:
The percentage of copper, carbon and oxygen are same in two samples, i.e., they are mixed at same proportions.

9th Class Physical Science Textbook Page No. 60

Question 12.
Are elements also made of atoms?
Answer:
When the particles of a substance contain only one type of atoms, that substance is called an element. In elements the smallest particle that exist may be atoms or molecules.

9th Class Physical Science Textbook Page No. 62

Question 13.
How do we write the symbols for calcium, chlorine, chromium?
Answer:
We have only 26 alphabets in English, but there are over 100 known elements. We cannot write the same symbol for carbon, calcium, chromium, etc.

9th Class Physical Science Textbook Page No. 63

Question 14.
Would you be able to recognise the elements of the table – 2, have symbols of this category?
Answer:
Yes. They are iron, gold, sodium, and potassium.

9th Class Physical Science Textbook Page No. 64

Question 15.
Observe the atomicity and fill the following table.

Answer:

Name of the element	Formula	Atomicity
Argon	Ar	Monoatomic
Helium	He	Monoatomic
Sodium	Na	Monoatomic
Iron	Fe	Monoatomic
Aluminium	Al	Monoatomic
Copper	Cu	Monoatomic
Hydrogen	H2	Diatomic
Oxygen	O2	Diatomic
Nitrogen	N2	Diatomic
Chlorine	Cl2	Diatomic
Ozone	O3	Triatomic
Phosphorus	P4	Tetratomic
Sulphur	S8	Octatomic

Question 16.
What is valency?
Answer:
Every element reacts with other element according to its combining capacity, which we call as its valency.

9th Class Physical Science Textbook Page No. 66

Question 17.
Can you write the formula of carbon dioxide and carbon monoxide? Try to write formula for them as we have done in case of water molecule.
Answer:
Carbon dioxide :
The elements present are carbon and oxygen. One atom of carbon and one atom of oxygen are present in a molecule of carbon monoxide. Hence the formula of carbon monoxide is CO.

Carbon dioxide :
The elements present are carbon and oxygen. One atom of carbon and 2 atoms of oxygen are present in a molecule of carbon dioxide. Hence the formula of carbon dioxide is CO₂.

9th Class Physical Science Textbook Page No. 69

Question 18.
How many molecules are there in 18 grams of water?
Answer:
6.022 × 10²³ molecules are there in 18 grams of water.

Question 19.
How many atoms are there in 12 grams of carbon?
Answer:
6.022 × 10²³ atoms are there in 12 grams of carbon.

9th Class Physical Science Textbook Page No. 58

Question 20.
Do you get the same result if the conical flask is not closed?
Answer:

1. No, we cannot get the same result.
2. When the conical flask is not closed, some gases will leave out the flask during chemical reaction.

Question 21.
Recall the burning of the magnesium ribbon in air. Do you think mass is conserved during this reaction?
Answer:

1. Yes, but we cannot observe the conservation of mass.
2. When the experiment is conducted in a closed container where there is no scope for oxygen to escape, we can observe the conservation of mass. But in this condition this experiment is not possible.

9th Class Physical Science Textbook Page No. 59

Question 22.
100 g of mercuric oxide decompose to give 92.6 g of mercury and 7.4 g of oxygen. Let us assume that 10 g of oxygen reacts completely with 125 g of mercury to give mercuric oxide. Do these values agree with the law of constant proportions?
Answer:
Proportion of oxygen = 7.4 : 10
Proportion of mercury = 92.6 : 125
\(\Rightarrow \frac{7.4}{10}=\frac{92.6}{125} \Rightarrow 0.74=0.74\)
∴ They follow law of constant proportions.

Question 23.
Discuss with your friends if the carbon dioxide that you breathe out and the carbon dioxide they breathe out are identical. Is the composition of the carbon dioxide of different sources same? (Page – 73)
Answer:
Same.
This can be justified with the help of law of constant proportions.

9th Class Physical Science Textbook Page No. 60

Question 24.
Which postulate of Dalton’s theory is the result of the law of conservation of mass?
Answer:
First postulate of Dalton’s theory i.e. “Matter consists of indivisible particles called atoms”, is the result of law of conservation of mass.

Question 25.
Which postulate of Dalton’s theory can explain the law of constant proportions?
Answer:
Third postulate of Dalton’s theory i.e. “Atoms of a given element have identical mass and chemical properties. Atoms of different elements have different masses and chemical properties”, is the result of law of constant proportions.

9th Class Physical Science 4th Lesson Atoms and Molecules Activities

Activity – 1

Question 1.
Some elements and their possible symbols are given. Correct them and give reasons for your corrections.
Answer:

Activity – 2

Question 2.
Write the symbols for given elements.

Answer:

AP State Syllabus AP Board 9th Class Social Studies Important Questions Chapter 2 The Natural Realms.

AP State Syllabus 9th Class Social Studies Important Questions 2nd Lesson The Natural Realms

9th Class Social 2nd Lesson The Natural Realms 1 Mark Important Questions and Answers

Question 1.
Write any two landforms which are formed by work of water? (SA-II : 2016 – 17)
Answer:
V-shaped valley. Deltas etc.

Question 2.
Give any one reason for the following. (SA-I : 2019 – 20)
Answer:
The majority of Earth’s volcanoes and earthquakes take place along the pacific basin. A. Plate boundaries are found all the way around the pacific basin.

9th Class Social 2nd Lesson The Natural Realms 2 Marks Important Questions and Answers

Question 1.
What are the effects of movements of tectonic plates. (SA-III : 2015 – 16)
Answer:

• The movement of these plates have changed the position and size of the continents over millions of years.
• These movements influenced the evaluation of the present land form features of India.
• The movement of plates form a chain of mountains.
• This process causes earthquakes etc.

Question 2.
Arrange the following concept in a correct manner in the given table. (SA-II : 2017 – 18)
Concept: Mushroom rock, Sea arches, plunge pool, U shaped valley.

Factors	Land forms
1. Work of water
2. Work of glaciers
3. Work of winds
4. Work of waves        .

Answer:

Factors	Land forms
1. Work of water	Plunge pool
2. Work of glaciers	U Shaped valley
3. Work of winds	Mushroom rock.
4. Work of waves        .	Sea arches

Question 3.
With reference to the Third Order Landforms, answer the following questions : (SA-I : 2019 – 20)
a) What are ‘Third Order Landforms’?
Answer:
The shaping of the landforms by wind and water are called ‘Third Order Landforms’.

b) What are the factors that cause their formation?
Answer:
Water, wind, glaciers and waves.

9th Class Social 2nd Lesson The Natural Realms 4 Marks Important Questions and Answers

Question 1.
Explain how air and water transform the surface of the Earth? (SA-II : 2018 – 19)
Answer:
The Air and water transform the surface of the earth by the four activities.
These are:
Weathering :
Water and moisture in the air also help this process. Water reacts with the chemicals of the rocks and further weakens the rock. These processes by which the rocks are weakened and broken are called “Weathering”.

Erosion :
Flowing water and wind have great power and can slowly wear away or cut away the rocks and soil cover in higher places. Water acts in many ways, as rain, river, flowing ground water, sea waves, glaciers etc. Wind too takes many forms like storms, gusts etc.

The active wearing away of the earth’s surface by these moving agents is called erosion.

Transportation :
The eroded material in the form of small rocks, gravel, mud fine soil etc. carried by winds and water is called transportation.

Deposition :
When the rivers and winds slow down, they do not have the force to carry the material any more and they dump them. This dumped debris help to form plains and river basins.

9th Class Social 2nd Lesson The Natural Realms Important Questions and Answers

Question 1.
What are the natural realms of the Earth? Describe them.
Answer:
There are four natural realms of the earth. They are

1. Lithosphere
2. Hydrosphere
3. Atmosphere
4. Biosphere.

1. Lithosphere:
The hard top part of the earth, the solid crust, which is made up of rocks and minerals and covered with a thick layer of soil. Soil is called lithosphere. It has high mountains, plateaus, plains, deep valleys and oceans. We and most other living beings live on this realm.

2. Hydrosphere :
The realm of water is called hydrosphere. It comprises various sources of water and different types of water bodies like rivers, lakes, seas, oceans, etc. and in the atmosphere in the form of water vapour and clouds. Life on earth is not possible without water.

3. Atmosphere :
The thin layer of air that surrounds the earth is atmosphere. It consists of a large number of gases including oxygen, nitrogen, carbon dioxide, water vapour, etc. and also dust particles. This cover of air is held around the earth by its gravitational force and rotates around the sun with the Earth.

4. Biosphere :
The realm of life including bacteria which live high on atmosphere or in deep oceans constitutes the biosphere. Life needs the presence of all the three realms, land, water and air. So life resides in the intersection of the three natural realms. Life also actively changes the three other realms.

Question 2.
What are called plates? How many plates are there on the earth?
Answer:
The massive base of rocks on which all the continents and even the oceans are actually situated are called plates. There are six major plates and several minor ones on the Earth. The African, North American, South American, Indo-Australian, Antarctic, Eurasian, and Pacific are the major plates. Nazca and Arabian are some among the minor plates.

Question 3.
What are plate tectonics? How are they caused?
Answer:

1. The plates actually float on the mantle.
2. They are constantly being pushed and therefore keep moving slowly.
3. As a result of this movement, one plate pushes another neighbouring plate.
4. One plate is pushed under into the mantle while the other plate is pushed up to form a chain of mountains.
5. This movement of plates is called plate tectonics.
6. Plate tectonics cause earthquakes.

Question 4.
What is called sea-floor spreading? How does it occur?
Answer:
The eruptions on the mid-ocean ridge create new ocean floor made of basalt rocks, which then spread literally from the ridge and this newest crust slowly pushes the plate away from the ridge, which is called ‘sea-floor spreading’.

Question 5.
How is the river deposition useful to man?
Answer:

1. As water in a river flows down a slope, it plucks sediment from the land. Other streams join it forming a broad river basin.
2. The water carries soil, sand and sediments down stream.
3. As the river reaches flatter ground, it slows down and drops the sediments there. This is called deposition.
4. The sediments build up a flood plain.
5. At the river’s mouth, the water loses its force, drops all its sediments and thus deltas are formed.
6. Flood plains and deltas make fertile farm land.
7. The sediments deposited in flood plains and deltas are called silt.
8. Silt is rich in nutrients.
9. Many ancient civilisations flourished in flood plains and deltas.

Thus the deposition of rivers are useful to man.

Question 6.
What are the landforms originated by the wind action?
Answer:
Strong winds carry sand and fine soil which strike the hard rocks. These too act as abrasive sand paper and erode the hard rocks. The wind action creates a number of interesting erosional and depositional features in the desert.

1. Sand Dunes :
Due to weathering and persistent wind action there is a large accumulation of fine sand in many deserts. These form ‘sand dunes’.

2. Mushroom Rock :
Winds erode the lower section of the rocks more than the upper part. Therefore such rocks have narrower bottom and wider top like mushrooms. So they are called mushroom rocks.

3. Inselberg:
The isolated residual hills rising abruptly from the ground are called inselberg or Island Mountain. They are characterized by their very steep slopes and rather rounded tops.

4. Loess Plains :
a) The fine dust, which is fertile and yellow in colour, is blown beyond the deserts and is deposited on neighbouring land. This soil is called Loess. Loess are in fact fine loam, rich in lime and extremely porous.
b) The plains formed by deposition of loess are called Loess Plains.

Question 7.
Name the landforms due to the Glacier action.
Answer:
1. Slow moving of mass of ice (a river of ice) is called Glacier.
2. A Glacier erodes through a process called “Plucking” in which it lifts pieces of rock and transports them.
3. The landforms created due to Glacier’s action are :
a) U shaped Valley:
Through the dual process of plucking and abrasion, glaciers create a “U shaped Valley”.

b) Moraines :
Pebbles, cobbles, sand etc., may be deposited at various parts of the
glaciers. The deposition of this till is called moraines. –

c) Huge rugged boulders:
The huge rocks, which cannot be carried by, are left behind in the form of huge rugged boulders.

d) Ozone :
Ozone is an inorganic molecule with the chemical formula 03. It is a pale blue gas with a distinctively pungent smell. Ozone’s 03 formula was determined in 1865.

Question 8.
Prepare a table showing depositional and erosional features separately.
Answer:

Features of deposition	Features of erosion
1. When the rivers and winds slow down they do not have the force to carry the materials any more and they dump them.	1. Flowing water and wind have great power. They can slowly wear away or cut away the rocks and soil cover in higher places.
2. This dumped debris helps to form plains and river basins.	2. Water as rain, river, flowing ground water, sea waves, glaciers is responsible for erosional activities.
3. Much of the debris is actually trans­ported by rivers to the sea. Layer after layer these deposits accumulate in the bottom and overtime get transformed to sedimentary rocks.	3. The active weathering away of the earth’s surface by these moving agents is called erosion.
4. The landforms formed because of deposition are 1. plains 2. deltas 3. meanders 4. ox-bow lakes and 5. sand dunes and beaches.	4. The landforms formed because of ero­sion are 1. V-shaped valleys 2. Gorges 3. Canyons 4. Plunge pools 5. U-shaped valleys 6. Inselberg 7. Mushroom rock, etc.

Question 9.
What are the natural realms of the Earth?
Answer:
There are four natural realms of the earth. They are

1. Lithosphere
2. Hydrosphere
3. Atmosphere and
4. Biosphere.

Question 10.
What are called plates?
Answer:
The massive base of rocks on which all the continents and even the oceans are actually situated are called plates.

Question 11.
What is called sea-floor spreading?
Answer:
The eruptions on the mid-ocean ridge create new ocean floor made of basalt rocks, which then spread literally from the ridge and this newest crust slowly pushes the plate away from the ridge, which is called ‘sea-floor spreading’.

Question 12.
What is Lithosphere?
Answer:
Lithosphere is the solid crust or the hard top part of the Earth. It is made up of rocks and minerals. It is covered with a thick layer of soil.

Question 13.
How many major plates are there on the earth? What are they?
Answer:
There are six major plates on the earth. They are African, North American, South American, Indo Australian, Antarctic, Eurasian and Pacific plates.

Question 14.
What is meant by intrusive landforms?
Answer:
Intrusive landforms :
Some part of the lava may not reach the surface and may cool under the surface and become rocks; These are called ‘intrusive landforms’.

Question 15.
Which are called ‘Third order landforms?
Answer:
The shaping of the landforms by wind and water is called ‘Third order landforms’ by geographers.

Question 16.
How is lithosphere useful to mankind?
Answer:

• Lithosphere is the solid crust or the hard top part of the earth.
• When it heats due to sunrays or cools down, it influences air and water too.
• We and most other living beings live on this realm.
• We use the rocks and soils and other things found in this hard crust in many ways.

Question 17.
What is the impact of vegetation on lithosphere?
Answer:

• Trees, plants and grass constitute vegetation.
• Vegetation contribute to the weathering of rocks by driving roots into fine cracks or holes in the rocks.
• They also enable water and moisture to enter into rocks which further enable weathering.
• On the other hand plant or grass cover on soils prevent easy denudation or transportation of soil by wind or water.

Question 18.
Which processes cause the formation of ‘Third Order landforms’?
Answer:

• The shaping of landforms by wind and water are called ‘third order landforms’.
• They include carved mountains, valleys, deltas, sand dunes, etc.
• Processes like weathering, erosion, transportation, and deposition are largely responsible for these landforms.

Question 19.
What do you mean by geomorphic cycle?
Answer:

• Landforms continuously keep on changing due to denudation activities.
• But these changes occur very slowly.
• The structure of mountains, plateaus and plains keep on changing through process known as ‘erosion cycle’ or ‘geomorphic cycle’.

Question 20.
How are gorges formed?
Answer:

• A gorge is almost equal in width at its top as well as its bottom.
• The Byson gorge in Andhra Pradesh on the Godavari, Indus gorge in Kashmir etc., are examples.
• Where the rocks are very hard, the river cuts a narrow valley, the sides are so steep that these ‘gorges’ are formed.

Question 21.
What is a canyon?
Answer:

• A canyon is characterised by steep like side slopes and may be as deep as a gorge.
• A canyon is wider at its top than bottom.

Question 22.
How ocean rocks or crust are formed?
Answer:
These are formed by lava rising up from the mantle. The eruptions on the ridges create new ocean floor made of basalt rocks, which then spreads laterally from the ridge. The first order landforms such as oceans and continents are formed at the time when the hot earth was cooling. While the earth’s interior continued to cool, it contracted and the outer crust wrinkled forming ridges i.e., mountains and basins i.e., oceans.

The second order landforms such as plains, plateaus and mountains are formed as a result of the internal processes of the earth. The third order landforms such as carved mountains, valleys, deltas, sand dunes are formed as a result of the shaping of the land forms by wind, water.

Question 23.
What are the four main “realms” of the earth? Explain how a cement factory world impact the various “realms”.
Answer:

• Realms are areas which have some common features.
• There are four major natural realms on the earth.
• They are :
  1. Lithosphere,
  2. Hydrosphere,
  3. Atmosphere and
  4. Biosphere.
• Cement factory is a mineral based industry.
• Unscientific way of mining may lead to earthquakes.
• Excessive emission of gases and dust may lead to air pollution.
• Heating of limestone and clay may emit mercury which may damage the brains of the children.

Question 24.
Write about “Plate tectonics”.
(OR)
What is plate tectonics?
Answer:

• The region where the two plates meet and push each other, a lot of pressure is exerted.
• One plate is pushed under into the mantle while the other plate is pushed up, to form a chain of mountains.
• This movement of plates is called ‘Plate tectonics’.

Question 25.
What are the two kinds of changes happening in the Lithosphere?
Answer:

• There are two kinds of changes taking place in the lithosphere.
• They are :
  a. The slow movement
  b. The sudden movement.
  3) The slow movement leads to the formation of the crust.
  4) The sudden movements (eruption of volcanoes and earthquakes) can be destructive and cause much damage.

Question 26.
How are Igneous rocks formed?
Answer:

• When volcano erupts, the molten material (also accompanied by steam, smoke and various gases) comes out from the depths of the earth.
• The molten materials cool on the earth and form hard rocks called “Igneous rocks”.

Question 27.
Write about “Intrusive landforms” and “Extrusive landforms”.
Answer:

• When volcano erupts, some part of the lava may not reach the surface and may cool under the surface and become rocks which are called “intrusive landforms”.
• A part of the lava which pours on the surface of the earth forms the “extrusive landforms”.

Question 28.
List out landforms originated due to the work of waves.
Answer:

• The erosion and deposition by the sea waves give rise to coastal landforms.
• “Sea Arches”, “Sea Cliff’, Cape, Bay and beaches are formed due to the work of the waves.

Question 29.
From which Greek word is the word Hydrosphere derived?
Answer:
It comes from the Greek word ‘hudor’ meaning water.

Question 30.
Write about the word Atmosphere.
Answer:
“Atmosphere” is derived from two greek words “atmos” means vapour and “sphaira” means sphere or ball.

Question 31.
Name few volcanoes that are situated in India.
Answer:
The Barren islands, and Narcondam are volcanoes situated in India.

Question 32.
What is weathering?
Answer:
The gradual disintegration of rocks by atmospheric forces or weather forces is called weathering.

Question 33.
What is erosion?
Answer:
The active wearing away of the earth’s surface, by different agents, is called erosion.

Question 34.
“The Earth is a deeply interconnected system” – Interpret the statement.
Answer:
The Earth consists of four major realms.

1. Lithosphere,
2. Hydrosphere,
3. Atmosphere and
4. Biosphere.

All these four are interrelated. All these four spheres together help the birth, existence, and continuance of life on Earth. Life needs the presence of all the other three realms land, water, and air. Life resides in the intersection of the three natural spheres. Life also actively changes the three other realms.

We cannot think of one realm without the crucial role of others. We cannot tamper with one aspect of it without affecting everything around us including ourselves. Thus we can say that the Earth is a deeply inter connected system.

Question 35.
“One day in very distant future the land you are standing upon will go under the Himalayas” – Interpret the above statement.
Answer:
At the margins of the plates where one plate meets another often the incoming plate dips under the stable plate. In fact the incoming plate actually goes into the mantle of the earth and becomes molten due to the heat of the mantle.

The plate thus going under into the mantle actually pulls the rest of the plate with it. For example, the Indian plate pushes the Eurasian plate and goes under if where the Himalayan mountains are.

Thus one day in very distant future the land we are standing upon will go under the Himalayas and join the mantle.

Question 36.
“The low lands what we see today were once mountains and plateaus” – Explain.
Answer:
External forces like water and air work vigorously to wear away the surface and the interaction of these constructive and destructive forces gives rise to the great diversity of present day landforms. These external processes on one hand wear away the surface of the rocks and mountains then they transport the wornout particles and deposit them in low lands and basins.

The processes of wearing away and deposition cause a general leveling of the surface. Processes like weathering, erosion, transportation and deposition are largely responsible for these landforms. It is known as denudation process.

Denudation is a continuous process. The landforms continuously keep on changing due to denudation activities. But these changes occur very slowly. Thus the low lands what we see today were once mountains and plateaus.

Question 37.
Read the paragraph and answer the following questions.
In some cases, where the rocks are very hard, the river cuts a very narrow valley, the sides are so steep that ‘Gorges’ are formed. The Byson gorge in A.P. on the Godavari, Indus Gorge in Kashmir are examples of this. Another important erosion form is Canyon. A Canyon is characterized by steep side slopes and may be as deep as a gorge. A gorge is almost equal in width at its top as well as its bottom.
1) Write any two similarities between gorges and canyons?
Answer:
a) It is as deep as gorge.
b) Both are formed with work of water.

2) Write any two differences between gorges and canyons?
Answer:
a) Canyon has a steep like side slope whereas gorge is too steep without side slope.
b) Canyon is wider at the top than at the bottom. Whereas Gorge is almost equal in width at its top as well as at its bottom.

3) Give an example of canyon.
Answer:
The Grand canyon on river Colorado.

4) How are gorges useful ?
Answer:
Gorges are suitable for construction of dams.

Question 38.
Last year (2015) Nepal witnessed a devastating earthquake. Learn about it.
Answer:

• Earthquake occured on 25th April 2015 and after shocks were felt on 12 May, 26th April, and 25th November of 2015.
• With a magnitude ranging from 7.8 to 8.1 on Richter scale, it caused a huge damage of about $ 5 billion.
• Nepal suffered 8,857 deaths and 21,952 persons were injured along with India, China, and Bangladesh.
• It’s hypocenter was at a depth of 8.21 cm and with epicenter was at east of district of hamjung.
• UNESCO world heritage sites in Khatmandu valleys and temples were damaged.
• It also triggered avalanche on Mount Everest causing as many as 200 deaths.
• It was believed to be the worst earthquake. Nepal suffered after 1934 Nepal-Bihar earthquake.

Question 39.
1. Locate different continents and oceans on the given world map.
Answer:

1. Asia
2. Europe
3. Africa
4. North America
5. South America
6. Australia
7. Pacific Ocean
8. Indian Ocean
9. Antarctic Ocean
10. Atlantic Ocean
11. Arctic Ocean

Question 40.
Observe the map and answer the following questions.

Which parts of India lie near plate margins?
Answer:

• The states of Gujarat, Rajasthan, Jammu and Kashmir lie near plate margins.
• So these areas are earthquake prone areas.

Question 41.
Label the patrs to the given diagram.
Answer:

1. Magma chamber
2. Lava
3. Central vent
4. Layers of lava and ash from past eruptions
5. Side vent

Question 42.
Why do you think glaciers make U-shaped valleys while rivers make V-shaped valleys?
Answer:
The shape of the trail left by the glacier is a function of the ice’s pressure on the ground. So if you look at the cross-section of a glacier is the laziest pattern the glacier can make, i. e. U. So the glaciers make U-shaped valleys.

In the high mountains, the flow of a river is very swift as it descends the steep slopes and it exerts a great force in cutting the mountain vertically. As a result a deep valley develops, narrow at the bottom and wide at the top. Thus V-shaped valleys are formed.

Question 43.
Appreciate the benefit with the eruption of a volcano?
Answer:

• There are various benefits with the eruption of volcano.
• Fertile soils are formed, like ones in deccan plateau.
• Valuable minerals from interior of the earth were brought to the surface or nearer to it.
• The soils formed like this are proved to be most populous areas, like in Java island.

AP State Syllabus AP Board 9th Class Physical Science Solutions Chapter 1 Motion Textbook Questions and Answers.

AP State Syllabus 9th Class Physical Science Solutions 1st Lesson Motion

9th Class Physical Science 1st Lesson Motion Textbook Questions and Answers

Improve Your Learning

Question 1.
As shown in following figure, a point traverses the curved path.
Draw the displacement vector from given points A to B.

Answer:

As the point traverses from A to B, the displacement is the shortest distance between A and B. Hence the displacement vector will be as follows.

Question 2.
“She moves at a constant speed in a constant direction.” Rephrase the same sentence in fewer words using concepts related to motion. (AS 1)
Answer:
“She moves with constant velocity”.

Reason :
Constant speed in a constant direction is nothing but ‘constant velocity’.

Question 3.
What is the average speed of a Cheetah that sprints 100 m in 4 sec? What if it sprints 50 m in 2 sec? (AS 1, AS7)
Answer:

Question 4.
Correct your friend who says, “The car rounded the curve at a constant velocity of 70 km/h”. (AS 1)
Answer:
“The car rounded the curve at a constant speed of 70 km/h”.

Reason :
In a circular motion, speed remains constant but velocity changes.

Question 5.
Suppose that the three balls shown in figure below start simultaneously from the top of the hills. Which one reaches the bottom first? Explain.

Answer:
Ball from first hill reaches the bottom first.
Reason :

1. In the first hill, the ball has uniform rectilinear motion.
2. So, the speed and velocity have same magnitude and direction.
3. In the second and third hills, the ball takes curved path.
4. So, the direction of velocity changes.

Question 6.
In the figure given below distance vs time graphs showing motion of two cars A and B are given. Which car moves fast? (AS 1)

Answer:
Car A moves fast.

Reason :

1. If we draw perpendiculars to X and Y axes from A and B respectively, we can observe that A covers large distance (S₁) within a short time (t₁).
2. Find the slopes of the lines OA and OB at any instant. Slope of OA is high. Hence car A moves faster.

Question 7.
Draw the distance vs time graph when the speed of a body increases uniformly. (AS 5)
Answer:
Let us consider a car moves as shown in the table.

Time (t) sec	Distance in meters
0 sec	0 meters
1 sec	3 meters
2 sec	6 meters
3 sec	9 meters
4 sec	12 meters
5 sec	15 meters

Now draw a s-t graph.

Question 8.
Draw the distance-time graph when its speed decreases uniformly. (AS 5)
Answer:
Let us consider the movement of a car after applying brakes.

Time (t) sec	Distance in meters
0 sec	20 meters
1 sec	18 meters
2 sec	16 meters
3 sec	14 meters
4 sec	12 meters
5 sec	10 meters

Now draw distance-time graph.

Question 9.
A car travels at a speed of 80 km/h during the first half of its running time and at 40 km/h during the other half. Find the average speed of the car. (AS 1, AS 7)
Answer:
Let the total running time = x hrs

Question 10.
A car covers half the distance at a speed of 50 km/h and the other half at 40 km/h. Find the average speed of the car. (AS 1, AS 7)
Answer:
Let the total distance = x km.
First half is covered with a speed of 50 km/h.

Question 11.
Derive the equation for uniform accelerated motion for the displacement covered in its n^th second of its motion. (s_n = u + a ( n – \(\frac{1}{2}\)) (AS 1)
Answer:
We know that distance travelled by an object in t seconds Is s = ut + \(\frac{1}{2}\) at²
∴ Distance travelled in ‘n’ seconds, s_{(n sec)} = un + \(\frac{1}{2}\)an² ………. (1)
Distance travelled in (n – 1) seconds, s_{(n – 1)} = u(n – 1) + \(\frac{1}{2}\) a(n – 1)² …….. (2)

Question 12.
A particle covers 10m in first 5 sec and 10m in next 3 sec. Assuming constant acceleration. Find initial speed, acceleration and distance covered in next 2 sec. (AS 1, AS 7)
Answer:
Distance covered in first 5 sec = 10

To find the distance covered in next 2 sec, we have to find the initial speed after 8 sec
i.e., the final velocity after 8 sec.

Question 13.
A car starts from rest and travels with uniform acceleration ‘α’, for some time and then with uniform retardation ‘β’ and comes to rest. The time of motion is “t”. Find the maximum velocity attained by it. (αβt/(α+β)) (AS 1, AS 7)
Answer:
Acceleration a = a m/sec²
Initial speed u = 0 m/sec
Let the time be t₁ sec.
From equation v = u + at
⇒ v = 0 + αt₁
\(\therefore \mathrm{t}_{1}=\frac{\mathrm{v}}{\alpha} \mathrm{sec}\)
Retardation a = – β m/sec²
Initial speed ‘u’ is equal to the final
velocity with acceleration ‘α’
= u = αt₁ m/sec
Final velocity v = 0 m/sec
Let the time be t₂ sec

Question 14.
A man is 48m behind a bus which is at rest. The bus starts accelerating at the rate of 1 m/s², at the same time the man starts running with uniform velocity of 10 m/s. What is the minimum time in which the man catches the bus? (AS 1, AS 7)
Answer:
Bus is at rest.
∴ u = 0; a = 1 m/sec²
Let the bus cover the distance ‘s’ in ‘n’ seconds.

A man running with uniform velocity, v = 10 m/sec.
Distance covered by man in n seconds = 10 nm.
But after ‘n’ seconds the man catches the bus.

∴ The minimum time in which the man catches the bus is 8 sec.

Question 15.
A body leaving a certain point “O” moves with a constant acceleration. At the end of the fifth second, its velocity is 1.5 m/s. At the end of the sixth second, the body stops and then begins to move backwards. Find the distance traversed by the body before it stops. Determine the velocity with which the body returns to point “0”. (AS 1)
Answer:
Velocity in 5^th sec = 1.5 m/sec ; The body comes to rest in 6^th sec.
∴ Final velocity in 6^th sec, v = 0
∴ Acceleration in 6^th sec is v = u + at ⇒ 0 = 1.5 + a. 1 ⇒ a = -1.5 m/sec²
[The velocity in 5^th sec becomes the initial velocity for 6^th sec]

After 6 sec, the body comes to rest.
∴ v = 0, a = -1.5 m/sec², u = ?, t = 6 sec.
v = u + at ⇒ 0 = u – 1.5 × 6 ⇒ u = 9 m/sec.
∴ Distance traversed by the body in 6 sec. i.e., before it stops.
s = ut + \(\frac{1}{2}\) at² = 9 × 6 + \(\frac{1}{2}\) × – 1.5 × 6² = 54 – 27 = 27m.
For backward journey,
u = 0 m/sec, t = 6 sec, a = -1.5 m/sec²
v = u + at ⇒ v = 0 – 1.5 × 6 ⇒ v = – 9
∴ Velocity for backward journey is – 9 m/sec.

Question 16.
Distinguish between speed and velocity.(AS 1)
Answer:

Speed	Velocity
1. The distance covered in unit time is called average speed.	1. The displacement of an object per unit time is called average velocity.
2. Speed = \(\frac{\text { Distance }}{\text { Time }}\)	2. Velocity =\(\frac{\text { Displacement }}{\text { Time }}\)
3. Speed is scalar.	3. Velocity is vector.
4. Speed gives the idea of how fast the body moves.	4. Velocity gives the idea of how fast the body moves in specified direction.

Question 17.
What do you mean by constant acceleration? ((AS 1)
Answer:

• Acceleration is the rate of change of velocity.
  2
• It gives an idea how quickly velocity of a body is changing.
• Acceleration is uniform, when in equal intervals of time, equal changes of velocity occurs.
• For example, while driving a car, if we steadily increase the velocity from 30 km/h to 35 km/h in 1 sec and 35 km/h to 40 km/h in the next second and so on. In this case the acceleration is 5km/h, is said to be constant acceleration.
  

Question 18.
When the velocity is constant, can the average velocity over any time interval differ from instantaneous velocity at any instant ? If so, give an example; if not, explain why. (AS 2, AS 1)
Answer:
No. Here velocity is constant.
∴ Average velocity over any time interval is same and the instantaneous velocity at any instant is same.

Ex : Let us consider a car moves on a straight road with constant velocity say 10 m/s.
1) Now let the distance covered (AB) by the car in 1 s = 10 m.

2) Distance covered in 2s (AC) = 20 m.
Average velocity from A to C is \(\frac{20 m}{2 s}\) = 10 m/s.

3) Instantaneous velocity at A or B or C at any point = 10 m/s.

Question 19.
Can the direction of velocity of an object reverse when its acceleration is constant? If so give an example; if not, explain why? (AS 2, AS 1)
Answer:
Yes. In case of a vertically projected body, while the body is moving up, the direction of velocity is upward, whereas while it is falling down, the direction of velocity is downward. Acceleration in both the cases is constant (numerically).

Question 20.
A point mass starts moving in a straight line with constant acceleration V’. At a time t after the beginning of motion, the acceleration changes sign, without change in magnitude. Determine the time t0 from the beginning of the motion in which the point mass returns to the initial position. (AS 1)
Answer:

Question 21.
Consider a train which can accelerate with an acceleration of 20 cm/s² and slow down with deceleration of 100 cm/s². Find the minimum time for the train to travel between the stations 2.7 km apart. (AS 1)
Answer:
Let the Acceleration of the train a = 20 cm/s²
Deceleration of the train β = 100 cm/s²
Distance between the two stations s = 2.7 km = 27 × 10⁴ cm
Let the minimum time for the train to travel between the two stations is t sec.

Question 22.
You may have heard the story of the race between the rabbit and tortoise. They started from same point simultaneously with constant speeds. During the journey, rabbit took rest somewhere along the way for a while. But the tortoise moved steadily with lesser speed and reached the finishing point before rabbit. Rabbit woke up and ran, but rabbit realized that the tortoise had won the race. Draw distance vs time graph for this story. (AS 5)
Answer:

1. OX – movement of tortoise.
2. OABC – movement of rabbit
3. Rabbit and tortoise start at O’.
4. After time tj rabbit is at A and tortoise is at P.
5. Rabbit takes rest up to time t₂.
6. After time t₂, tortoise is at Q, but rabbit has no displacement.
7. After time t₃, the tortoise reaches the destination ‘X’.
8. But rabbit reaches the destination after time t₄.

Question 23.
A train of length 50 m is moving with a constant speed of 10 m/s. Calculate the time taken by the train to cross an electric pole and a bridge of length 250 m. (AS 1)
Answer:
Length of the train 50 m.; Speed of the train v = 10 m/s.
Distance travelled while crossing an electric pole = Length of the train = s = 50 m.
∴ Time taken to cross the electric pole ‘t’ = \(\frac{s}{v} \Rightarrow t=\frac{50}{10}\) = 5 s.
Length of the bridge = 250 m.
Distance travelled while crossing the bridge = Length of train + Length of bridge
= 50 + 250 = 300 m.
∴ Time taken to cross the bridge = \(\frac{300 \mathrm{~m}}{10 \mathrm{~m} / \mathrm{s}}\) = 30 sec.

Question 24.
Two trains each of having a speed of 30 km/h are headed at each other in opposite direction on the same track. A bird flies off one train to another with a constant speed of 60 km/h when they are 60 km apart till before they crash. Find the distance covered by the bird and how many trips the bird can make from one train to the other before they crash. (AS 1)
Answer:
Speed of each train = 30 km/hr
Speed of the bird = 60 km/hr
Distance between the two trains = 60 km
These two trains crash in one hour.
The bird flies a distance of 60 km till before the two trains crash.
The bird can make number of trips (infinity) before they crash.

Question 25.
A Stone dropped from top of a well reaches the surface of water in 2 seconds, find the velocity of stone while it touches the surface of water and what is the depth of the water surface from top of well (g=10m/s²) (Using V = U + at, S = Ut + 1/2 at²)
Answer:
Given that
t = 2s
u = 0 m/s [∵ free fall body]
v = ?
Depth s = ?
a = g = 10 m/s²

i) v = u + at
v = 0 + 10 × 2 = 20 m/s

ii) s = ut + – \(\frac{1}{2}\)at²
= 0 + \(\frac{1}{2}\) × 10 × 2²
= \(\frac{1}{2}\) × 10 × 4
= 20 m
Hence, velocity of stone while it touches the surface of water = 20 m/s
Depth of the water surface from the top of well = 20 m.

Question 26.
An object moving with 6m per second execute an acceleration 2 m/s² in next 3 seconds. How much distance it covered? (s = ut + 1/2 at²)
Answer:
u = 6 m/s; t = 3 sec; a = 2 m/s²
s = ut + \(\frac{1}{2}\) at²
= 6 × 3 + \(\frac{1}{2}\) × 2 × 3² = 18 + 9 = 27 m
The object covers 27 m in 3 sec.

Question 27.
A car stopped after travelling distance 8 m due to applying brakes at the speed of 40 m/s. Find acceleration and retardation of car in that period, (v² – u² = 2as)
Answer:
Here u = 40 m/s; v = 0 (vehical stopped); s = 8 m; a =?
v² – u² = 2as 0 – 40² = 2 × a × 8
a = \(\frac{-(40)(40)}{2 \times 8}\) =-100m/s
Acceleration = 100 m/s² with retordation on (-sign).

9th Class Physical Science 1st Lesson Motion InText Questions and Answers

9th Class Physical Science Textbook Page No. 1

Question 1.
If earth is in motion, why don’t we directly perceive the motion of the earth?
Answer:
Earth is in motion. We, the people on the earth also move with a speed equal to that of the earth. We cannot directly perceive the motion of the earth, because of this.

Question 2.
Are the walls of your classroom at rest or in motion? Why?
Answer:
The walls are at rest in view of our observation. When we discuss this in view of the motion of the earth, the walls are also in motion.

Question 3.
Have you ever experienced that the train in which you sit appears to move when it is at rest? Why?
Answer:
This happens when we sit in a stationary train and, the train on another track starts moving.

9th Class Physical Science Textbook Page No. 2

Question 4.
Why do we observe these changes?

Answer:
These changes are due to the point of observation. We know that earth is a sphere, the upward direction of the vertical position on its surface decisively depends upon the place on the earth’s surface, where the vertical is drawn.

Question 5.
Are the terms relative or not?
Answer:
The terms “longer”, “shorter”; “up” and “down”, etc. are relative to each other.

9th Class Physical Science Textbook Page No. 4

Question 6.
What answer may the passenger give to the driver?
Answer:
The car is in motion with respect to the observer on the road, but at rest with respect to the passenger. Because motion is a combined property of the observer and the body which is being observed.

Question 7.
How do we understand motion?
Answer:
A body is said to be in motion when its position is changing continuously with time relative to an observer.

9th Class Physical Science Textbook Page No. 6

Question 8.
Can you measure the average speed and average velocity?
Answer:
Yes, we can measure the average speed and average velocity.

Question 9.
How can you differentiate speed and average velocity?
Answer:

1. Speed gives the idea of how fast the body moves.
2. Velocity is the speed of an object in a specified direction.

9th Class Physical Science Textbook Page No. 7

Question 10.
Can you find the speed of the car at a particular instant of time?
Answer:
Yes, we can find the speed of the car at any instant of time by looking at its speedometer

Question 11.
What is the speed of the car at the instant of time ‘t₃‘ for given motion?
Answer:

The instantaneous speed is represented by the slope of the curve at a given instant of time. We can find the slope of the curve at any point on it by drawing a tangent to the curve at that point. The slope of the curve gives speed of the car at that instant.

9th Class Physical Science Textbook Page No. 8

Question 12.
In what direction does an object move? Distance vs time graph
Answer:
The object moves in the direction tangential to the direction of the motion of the string.

Question 13.
Which motion is called uniform? Why?
Answer:
The motion of the body is said to be in uniform when its velocity is constant.

9th Class Physical Science Textbook Page No. 9

Question 14.
What is the shape of the graph?
Answer:

The shape of the graph for a body which is in uniform motion is a straight line as shown in the figure.

9th Class Physical Science Textbook Page No. 10

Question 15.
a) What is the shape of the graph?
Answer:
It is a curve.

b) Is it a straight line or not? Why?
Answer:
The graph is not a straight line because the speed is changing irregularly.

Question 16.
Draw velocity vectors in the given figure at times t = 0, 1s, 2s, 3s.
Answer:

From the graph, we conclude that when the ball moves down the inclined plane its speed increases gradually but its direction remains constant.

9th Class Physical Science Textbook Page No. 11

Question 17.
Draw velocity vectors at times t = 1s, 2s, 3s in the given figure.
Answer:

From the graph, we conclude that when the ball moves up the inclined plane its speed decreases gradually, but the direction of motion remains constant.

Question 18.
Can you give few examples for motion of an object where its speed remains constant but velocity changes?
Answer:
For the bodies which are in uniform in circular motion the speed remain constant but velocity change. Ex : Rotation of earth, revolution of moon around the earth, etc.

Question 19.
Is the direction of motion constant? How?
Answer:
No, the direction of motion also changes continuously.

Question 20.
Can you give some more examples where speed and direction simultaneously change?
Answer:
Motion of a rocket, horizontally projected body, kicked football, a cricket ball bowled by a bowler, etc.

9th Class Physical Science Textbook Page No. 12

Question 21.
What is acceleration? How can we know that a body is accelerating?
Answer:

1. Acceleration gives an idea how quickly velocity of a body changing.
2. It is equal to the rate of change in velocity.
3. While travelling in a bus or car, when the driver presses the accelerator, the passen¬gers sitting in the bus experience acceleration. Their bodies press against the seats due to acceleration.

Question 22.
At which point is the speed maximum?
Answer:
At B, the speed will be maximum.

Question 23.
Does the object in motion possess acceleration or not?
Answer:
Any object which is in motion possesses acceleration.

9th Class Physical Science Textbook Page No. 5

Question 24.
What is the displacement of the body if it returns to the same point from where it started? Give one example from daily life.
Answer:
When a body returns to the same point where it is started, then the displacement is zero.
Ex: A man starts from his home, goes to a market and returns home. Then his displacement is zero.

Question 25.
When do the distance and magnitude of displacement become equal?
Answer:
The distance and the magnitude of displacement become equal when the body moves along a straight line in one direction.

9th Class Physical Science Textbook Page No. 6

Question 26.
What is the average speed of the car if it covers 200 km in 5 h?
Answer:
Distance = 200 km ; Time = 5 h

Question 27.
When does the average velocity become zero?
Answer:
The average velocity of a body becomes zero when its displacement is zero.

Question 28.
A man used his car. The initial and final odometer readings are 4849 and 5549 respectively. The journey time is 25h. What is his average speed during the journey?
Answer:
Distance covered = 5549 – 4849 = 700 km.
Time = 25h.

9th Class Physical Science Textbook Page No. 9

Question 29.
Very often you must have seen traffic police stopping motorists or scooter drivers who drive fast and fine them. Does fine for speeding depend on average speed or instantaneous speed? Explain.
Answer:
Instantaneous speed.

Question 30.
One airplane travels due north at 300 km/h and another airplane travels due south at 300 km/h. Are their speeds the same? Are their velocities the same? Explain.
Answer:

1. Speed is same.
2. Velocities are same in magnitude but differs in direction in the observer’s point of view.

Question 31.
The speedometer of the car indicates a constant reading. Is the car in uniform motion? Explain.
Answer:
Yes.

1. The indicator in speedometer changes its position even for a small change in speed.
2. As it indicates a constant reading, the car moves equal distances at equal intervals of time.
3. Hence the motion is uniform.

9th Class Physical Science Textbook Page No. 11

Question 32.
An ant is moving on the surface of a ball. Does it’s velocity change or not? Explain.
Answer:
Velocity changes.
As the ant is moving on the surface of a ball, it has to go in circular motion.

Question 33.
Give an example of motion where there is a change only in speed but no change in direction of motion.
Answer:
Motion of a bus on the road.

9th Class Physical Science Textbook Page No. 13

Question 34.
What is the acceleration of a race car that moves at constant velocity of 300 km/h?
Answer:
Velocity = 300 km/h = \(300 \times \frac{5}{18}=\frac{500}{6}\) = 83.33 m/sec
As the velocity is constant, the acceleration is also constant.
∴ Acceleration = 83.33 m/sec².

Question 35.
Which has the greater acceleration, an airplane, that goes from 1000 km/h to 1005 km/h in 10s or a skateboard that goes from zero to 5km/h in 1 second?
Answer:

Question 36.
What is the deceleration of a vehicle moving in a straight line that changes its velocity from 100 km/h to a dead stop in 10 sec?
Answer:

Question 37.
Correct your Mend who says “Acceleration gives an idea of how fast the position changes.”
Answer:
“Acceleration gives the idea of how fast the position changes in a given direction.”

9th Class Physical Science 1st Lesson Heat Activities

Activity 1 Distance and Displacement

Question 1.
Draw a graph showing the difference between distance and displacement.
Answer:

• Take a ball and throw it into the air with some angle to the horizontal.
• Observe its path and draw it on paper.
• The figure shows the path taken by the ball.
• The distance ASB gives the distance travelled by the ball.
• The length of \(\overrightarrow{\mathrm{AB}}\) gives the displacement of the ball.

Displacement:
Displacement is the shortest distance between initial and final points in a specified direction represented by a vector.

Distance :
Distance is the length of the path traversed by an object in a given time interval.

Activitie – 2 Drawing displacement vectors

Question 2.
Draw displacement vectors from A to B in the following situations.

Answer:

Activitie – 3 Measuring the average speed

Question 3.
How can the average speed be measured?
Answer:

1. Select two positions (say A and B) 50 meters apart in the ground.
2. Ask some students to stand at point A.
3. Ask another group of students with stop watches to stand at B.
4. When you clap your hand, the students at A start running towards the point B in any direction or path.
5. At the same time the students at B start their stop watches.
6. Observe that for each runner there is a student at B to measure the time taken for completing the race.
7. Note the time taken by each student to cover the distance between the points A and B in the table given below.
   

   Student	Time taken to reach B (Sec.)	Average speed (50 ft) m/s
   A1	t1	………
   A2	t2	………
   A3	t3	………

8. The student who took the least time to reach B (from A) is said to be the fastest runner.
9. The student who is fastest runner has the greatest average speed.
10. Thus we measure the average speed of any moving body.

Activity – 4 Observing the direction of motion of a body

Question 4.
Show that the direction of velocity is tangent to the path at a point of interest when a body is in uniform circular motion.
Answer:

• Carefully whirl a small object on the end of the string in the horizontal plane.
• Release the object while it is whirling on the string.
• We observe that the body along the tangent at the point where we released the body.
• Try to release the object at different points on the circle and observe the direction of motion of object after it has been released form the string.
• We will notice that the object moves on a straight line along the tangent to the circle at the point where we released it.

Activity – 5 Understanding uniform motion

Question 5.
Describe uniform motion.
Answer:
1) Consider a cyclist moving on a straight road.
2) The distance covered by him with respect to time is given in the following table.

Time (t in seconds)	Distance (s in meters)
0	0
1	4
2	8
3	12
4	16
–	–

3) Draw distance vs time graph for the given values in the table.

4) The graph will be as shown in the figure.
5) The straight line graph shows that the cyclist covers equal distances in equal inter¬vals of time.
6) If the direction of motion of the cyclist is assumed as constant, then we conclude that velocity is constant.
7) The motion of the body is said to be uniform when its velocity is constant.

Activity – 6 Observing the motion of a ball on an inclined plane

Question 6.
Describe an activity to explain the situation that “the speed changes but the direction of motion remains constant”.
Answer:
1) Set up an inclined plane as shown in the figure.
2) Take a ball and release it from the top of the inclined plane.
3) The positions of the ball at various times are shown in the figure given below.

4) On close observation we find that when the ball moves down on the inclined plane, its speed increases gradually, and the direction of motion remains constant on inclined plane.
5) Now push the ball till it acquires certain speed and release it with that speed from the bottom of the inclined plane.

6) We observe that the ball moves upward to a certain distance and comes back to the bottom.
7) From this we conclude that the speed changes but the direction of motion remains constant.

Activity – 7 Observing uniform circular motion

Question 7.
Explain with an example where “speed remains constant, but its velocity changes”.
Answer:

• Whirl continuously a stone which is tied to the end of the string.
• Draw its path of motion and velocity vectors at different positions as shown in figure.
• Assume that the speed of stone is constant.
• We observe that the path of the stone is a circle, and the direction of velocity changes at every instant of time, but the speed is constant.
• In this activity, we observe that though speed remains constant, its velocity changes.

Activity – 8 Observing the motion of an object thrown into air

Question 8.
Explain an activity to observe where speed and direction of motion change continuously.
Answer:

• Throw a stone into the air by making some angle with the horizontal.
• The path of the stone and velocity vectors are as shown in the figure.
• Here we observe that the speed of stone is not uniform as it traverses different distances at different intervals of time and finally comes to rest.
• The direction of motion is also not constant, as shown by the velocity vectors.
• In this activity, we noticed that the speed and direc¬tion of motion both change continuously.

Lab Activity

Question 9.
Describe an activity to find the acceleration and velocity of an object moving on inclined track.
Answer:
Aim : To find the acceleration and velocity of an object moving on an inclined track. Materials required: Glass marbles, book, digital clock, long plastic tubes and steel plate.
Procedure:

• Take a long plastic U type flat electrical wire cassing channel of length nearly 200 cm. Use this channel as track.
• Mark the readings in cm, along the track.
• Place one end of the track on a book and the other end on the floor.
• Keep a steel plate on the floor at the bottom of the track.
• Consider the reading at the bottom of the track as zero.
• Take a marble having enough size to travel in the track freely.
• Now release the marble freely from a certain distance say 40 cm.
• Start the digital clock when the marble is released.
• It moves down on the track and strikes the steel plate.
• Stop the digital clock when a sound is produced.
• Repeat the same experiment for the same distance 2 to 3 times and note the values of times in the table.

• Repeat the same experiment or various distances.
• Draw s -1 graph for above values.
• Do the above experiment by various slopes of the track and find acceleration in each case.

Conclusions :

1. As the slope increases, acceleration increases.
2. When iron block is used, we obtain the same conclusion as above. (The numerical values are less than the numerical values when marble is used)

AP State Syllabus AP Board 9th Class Physical Science Solutions Chapter 2 Laws of Motion Textbook Questions and Answers.

AP State Syllabus 9th Class Physical Science Solutions 2nd Lesson Laws of Motion

9th Class Physical Science 2nd Lesson Laws of Motion Textbook Questions and Answers

Improve Your Learning

Question 1.
Explain the reasons for the following. (AS 1)
a) When a carpet is beaten with a stick, dust comes out of it.
Answer:

1. The dust particles in the carpet are at rest.
2. When the carpet is beaten with a stick, the state of rest of the dust particles is disturbed.
3. Due to inertia, the dust particles comes out.

b) Luggage kept on the roof of a bus is tied with a rope.
Answer:

1. Luggage kept on the roof of a bus is in the state of rest.
2. As the bus moves, the luggage also moves with a velocity equal to the velocity of the bus.
3. If the bus suddenly stops, the luggage resists to change its state of motion.
4. Hence due to inertia it will fall down.
5. To avoid this, the luggage is tied with a rope.

c) A pace bowler in cricket runs in from a long distance before he bowls.
Answer:

1. When he runs in from a long distance, he gains momentum of inertia.
2. Due to this larger inertia, larger force is applied in a short interval of time.
3. Hence the momentum will be more.

Question 2.
Two objects have masses 8 kg and 25 kg. Which one has more inertia? Why? (AS 1)
Answer:

1. The object with mass 25 kg has more inertia.
2. The resistance to change the state of object will be more for a body of larger mass.

Question 3.
Keep a small rectangular shaped piece of paper on the edge of a table and place an old five rupee coin on its surface vertically as shown in the figure below. Now give a quick push to the paper with your finger. How do you explain inertia with this experiment?

Answer:

1. The coin and the paper are in inertia of rest.
2. When we give a quick push to the paper, paper comes to inertia of motion and the coin remains in its original state i.e., inertia of rest.
3. As a result, the paper will come out and the coin remains on the table without changing its position.

Question 4.
If a car is travelling westwards with a.constant speed of 20 m/s, what is the resultant force acting on it? (AS 1, AS 7)
Answer:

1. A car is moving with a constant speed.
2. Hence the net force on the car is zero both in horizontal and vertical directions.

Question 5.
What is the momentum of a 6.0 kg bowling ball with a velocity of 2.2 m/s? (AS 1)
Answer:
Mass of the ball (m) = 6.0 kg
Velocity of the ball (v) = 2.2 m/s
Momentum (p) = nv = 6.0 kg × 2.2 m/s = 13.2 kg m/s (or) 13.2 N-s

Question 6.
Two people push a car for 3 sec, with a combined net force of 200 N. (AS 1)
a) Calculate the impulse provided to the car.
Answer:
F_net = 200 N ; ∆t =3 sec
Impulse ∆p = F_net. ∆t = 200 × 3 = 600 N – sec.

b) If the car has a mass of 1200 kg, what will be its change in velocity?
Answer:
Mass of the car (m) = 1200 kg.; Net force (F_net) = 200 N
Time ∆t = 3 sec. ; Change in velocity ∆v =?

Question 7.
What force is required to produce an acceleration of 3 m/sec2 in an object of mass 0.7 kg? (AS 1)
Answer:
Mass of the object (m) = 0.7 kg.; Acceleration (a) = 3 m/sec²
Force required (F) = ?
F = ma = 0.7 x 3 = 2.1 N

Question 8.
A force acts for 0.2 sec on an object having mass 1.4 kg initially at rest. The force stops to act but the object moves through 4 m in the next 2 seconds, find the magnitude of the force. (AS 1)
Answer:

Velocity after 0.2 sec v = u + at = 0 + 0.2 a = 0.2a ……….. (1)
After 0.2 s, the body moves with uniform velocity, acceleration is zero, because force is removed.
∴ Velocity v = \(\frac{s}{t}=\frac{4}{2}\) =2 m/s. ………. (2)
From (1) & (2)
v = 0.2a ⇒ 2 = 0.2a
⇒ a = \(\frac{2}{0.2}\) = 10 m/s²
∴ Force applied F = ma = 1.4 kg × 10 m/s² = 14 N.

Question 9.
An object of mass 5 kg is moving with a velocity of 10 ms^-1. A force is applied so that in 15 s, it attains a velocity of 25 ms^-1. What is the force applied on the object? (AS 1)
Answer:
Mass (m) = 5 kg ; Initial velocity (u) = 10 m/s.; Time (t) = 15 s
Final velocity (v) = 25 m/s.
Acceleration a = \(=\frac{v-u}{t}=\frac{25-10}{15}=\frac{15}{15}=1 \mathrm{~m} / \mathrm{s}^{2}\).
Force applied on the object F = ma = 5 × 1=5 N.

Question 10.
Find the acceleration of body of mass 2 kg from the figures shown. (AS 1)

Answer:
1) Force 30 N is acting downwards on weight of (2 × 10) = 20 kg.
The acceleration a = \(\frac{30-20}{2}=\frac{10}{2}\) = 5 m/s²

2) m₁ = 2 kg, m₂ = 3 kg.
m₂ pulls the body mt with a weight 3 × 10 = 30 N.
∴ Acceleration of m₁ = \(\frac{30-20}{3+2}=\frac{10}{5}\)
= 2 m/s².

Question 11.
Take some identical marbles. Make a path or a track keeping your notebooks on either side so as to make a path in which marbles can move. Now use one marble to hit the other marbles. Take two, three marbles and make them to hit the other marbles. What can you explain from your observations? (AS 5)
Answer:

1. When one marble is hit by another marble, both the marbles move with some velocity.
2. When the marble is hit by two, three marbles, all marbles move with a velocity which is more than in the previous case.
3. As we are hitting with more marbles, the mass increases. So that the net momentum also increases.

Question 12.
A man of mass 30 kg uses a rope to climb which bears only 450 N. What is the maximum acceleration with which he can climb safely? (AS 1, AS 7)
Answer:
Mass m = 30 kg. ; Force F = 450 N
Acceleration a = ?
F = ma
∴ a = \(\frac{\mathrm{F}}{\mathrm{m}}=\frac{450}{30}\) =15 m/sec²
∴ The required acceleration =15 m/sec²

Question 13.
An vehicle has a mass of 1500 kg. What must be the force between the vehicle and the road if the vehicle is to be stopped with a negative acceleration of 1.7 m/sec²? (AS 1, AS 7)
Answer:
Mass of the vehicle, m = 1500 kg.; Acceleration (-a) = 1.7 m/sec²
Force, F =?
F = m (-a) = 1500 × (-1.7) = ( – ) 2550 N
∴ The force between the vehicle and road is 2550 N, in the direction opposite to that of the vehicle.

Question 14.
If a fly collides with the windshield of a fast moving bus, is the impact force experienced, same for the fly and the bus? Why? (AS 1, AS 2)
Answer:
The impact force experienced by the fly will be more, because the mass of fly is negligible when compared to the mass of the bus.

Question 15.
A truck is moving under a hopper with a constant speed of 20 m/sec. Sand falls on the truck at a rate 20 kg/s. What is the force acting on the truck due to falling of sand? (AS 1, AS 7)
Answer:
Mass of the sand falling on the truck in 1 sec = 20 kg
Constant speed of the truck = 20 m/s
Acceleration in 1 sec, a = \(\frac{\Delta v}{\Delta t}=\frac{20}{1}\) = 20 m/sec²
Force applied on the truck, F = ma = 20 kg x 20 m/sec² = 400 N

Question 16.
Two rubber bands stretched to the standard length cause an object to accelerate at 2 m/sec². Suppose another object with twice the mass is pulled by four rubber bands stretched to the standard length. What is the acceleration of the second object? (AS 1)
Answer:
First object:
Let the force applied by two rubber bands = F₁ Newton
Mass of the object = m₁ kg; Acceleration a₁ = 2 m/sec²
We know F = ma
F₁ = m₁ × 2
⇒ F₁ = 2m₁ …….(1)

Second object:
The force applied by 4 rubber bands = 2F₁ Newton
Mass of the object = 2m₁ kg ; Acceleration a₂ =?
We know F = ma
2F₁ = 2m₁. a₂

∴ Acceleration of the second object = 2 m/sec²

Question 17.
Illustrate an example of each of the three laws of motion. (AS 1)
Answer:
First law of motion :
A body continues its state of rest or of uniform motion unless a net force acts on it.
Ex:

1. When the bus which is at rest begins to move suddenly, the person standing in the bus falls backward.
2. When you are travelling in bus, the sudden stop of the bus makes you fall forward.

Second law of motion :
The rate of change of momentum of a body is directly proportional to the net force acting on it and it takes place in the direction of net force.
Ex : Place a ball on the veranda and push it gently. Then the ball accelerates from rest. Thus, we can say that force is an action which produces acceleration.

Third law of motion :
If one object exerts a force on the other object, the second object exerts a force on the first one with equal magnitude but in opposite direction.

Ex :

1. When birds fly, they push the air downwards with their wings, and the air pushes back the bird in opposite upward direction.
2. When a fish swims in water, the fish pushes the water back and the water pushes the fish with equal force but in opposite direction.
3. A rocket accelerates by expelling gas at high velocity. The reaction force of the gas on the rocket accelerates the rocket in a direction opposite to the expelled gases.

Question 18.
Two ice-skaters initially at rest, push of each other. If one skater whose mass is 60 kg has a velocity of 2 m/s. What is the velocity of other skater whose mass is 40 kg? (AS 1, AS 7)
Answer:
Mass of first skater m₁ = 60 kg.;
Velocity of first skater v₁ = 2 m/s.
Mass of second skater m₂ = 40 kg.; Velocity of second skater v₂ =?
As the two skaters push each other, the resultant momentum will become zero.
The resultant momentum m₁v₁ + m₂v₂ = 0

∴ Velocity of second skater is 3 m/s, but in the direction opposite to the first skater.

Question 19.
A passenger in moving train tosses a coin which falls behind him. It means that the motion of the train is (AS 7)
a) Accelerated
b) Uniform
c) Retarded
d) Circular motion
Answer:
a) Accelerated

Question 20.
A horse continues to apply a force in order to move a cart with a constant speed. Explain. (AS 1)
Answer:

1. The cart moves when the force (in the form of pulling) is applied by the horse.
2. As the horse and cart are moving, the net momentum will be zero at any instance of time.
3. Hence when the horse comes to rest, the cart also comes to rest.
4. To avoid this and to move the cart with a constant speed, the horse must apply force continuously.

Question 21.
A force of 5 N produces an acceleration of 8 m/sec² on a mass m, and an acceleration of 24 m/sec² on a mass m₂. What acceleration would the same force provide If both the masses are tied together? (AS 1)
Answer:
For the first mass (m₁)
Force F = 5 N
Acceleration a = 8 m/s²
We know, F = ma
5 = m, . 8
m₁= \(\frac{5}{8}\) kg

For the second mass (m₂)
Force F = 5 N
Acceleration a = 24 m/sec²
We know, F = ma
5 = m₂.24
m₂ = \(\frac{5}{24}\) kg
When both the masses are tied together and the same force is applied, then

Question 22.
A hammer of mass 400 g, moving at 30 m/s, strikes a nail. The nail stops the hammer in a very short time of 0.01 s. What is the force of the nail on the hammer? (AS 1)
Answer:
Mass of the hammer (m) = 400 g = 0.4 kg. ; Velocity of the hammer (v) = 30 m/s.
Momentum (∆p) = 30 × 0.4 N – s.
The nail stops the hammer with in a time 0.01 s.
∴ ∆t = 0.01 s.
The stopping force of the nail on the hammer.

Question 23.
System is shown in figure. Assume there is no friction. Find the acceleration of the liloc-ks-and tension in the string. Take g = 10 m/s² (AS 1)

Answer:
m₁ = 3 kg, m₂ = 3 kg.
1) Acceleration ’a’ and tension T on m₁ are shown in figure.
2) Acceleration a and tension T will be as shown in figure.

Normal force = weight 3s – T = 3a ………… (2)
∴ only tension applied
Tension T = 3 kg × a = 3a
From (1) & (2)
3g – 3a = 3a ⇒ 3g = 6a ⇒ a = \(\frac{3 g}{6}=\frac{3 \times 10}{6}\) = 5 m/s².
Tension T = 3a = 3 × 5 = 15 N.

Question 24.
Three identical blocks, each of mass 10 kg, are pulled as shown on the hoii ;ontal frictionless surface. If the tension (F) in the rope is 30 N, what is the acceleration oi each block? And what are the tensions in the other ropes? (Neglect the masses of the ropes) (AS 1)

Answer:
Three blocks, each of mass 10 kg are pulled by a rope.
∴ Total mass = 10 + 10 + 10 = 30 kg
Force applied by the rope, F = 30 N
∴ Acceleration of each block, a = \(\frac{F}{m}=\frac{30}{30}\) = 1 m/sec².

Tension in first rope (T₁)
First rope pulls only one block whose mass is 10 kg with an acceleration 1 m/sec².
∴ F = ma = 10 kg × 1 m/sec² = 10 N

Tension in second rope (T₂)
Second rope pulls two blocks, each of mass 10 kg.
∴ Total mass = 10 + 10 = 20 kg.
Acceleration, a = 1 m/sec²
Force, F = ma = 20 × 1 = 20 N

Question 25.
A ball of mass’m’ moves perpendicularly to a wall with a speed v, strikes it and rebounds with the same speed in the opposite direction. What is the direction and magnitude of the average force acting on the ball due to the wall? (AS 7)
Answer:
According to the Newton s third law of motion,
Force exerted by ball on the wall = – (Force exerts by the wall on the ball)
∴ F_B.W = – F_W.B
Force exerted by ball :
Mass of ball = m, speed = v, F_BW = ma = \(\frac{\mathrm{m} \cdot \mathrm{v}}{\mathrm{t}}\)
As the wall is at rest and exerts some force on the ball of mass m, then it moves in the other direction with the same speed.

Question 26.
Divya observed a horse pulling a cart. She thought that cart also pulls the horse with same force in opposite direction. As per third law of motion, the cart should not move forward. But her observation of moving cart raised some questions in her mind. Can you guess what questions are raised in her mind? (AS 2)
Answer:

• According to Newton’s third law, when horse pulls a cart, the cart also pulls the horse with same force but in opposite direction. So the cart has to stop. Why is the cart moving?
• What is the effect of friction of ground on the cart and horse?
• Does the cart continue to move even if the horse stops pulling it?
• What makes the cart to move continuously?
• Does it become an isolated system?
• What is the action and reaction in this system?

Question 27.
How do you appreciate Galileo’s thought of “any moving body continues in the stale only until some external force acts on it”, which is contradiction to the Aristotle’s belief of “any moving body naturally comes to rest”? (AS 6)
Answer:

• Science is dynamic.
• All theories can change time to time so that the science and technology will be developed.
• Aristotle’s belief proved to be wrong only by the experiments conducted by Galileo.
• So anybody can challenge the existing theories with proper experimentation.
• Aristotle’s and Galileo’s contradictory thought lead Newton to propose most popular laws of motion.
• Newton’s third law of motion is the basic principle in rocket launching.
• Nowadays we are enjoying the results of satellites launched by rockets.
• Hence comfortable life is the effort on experiments, theories, and calculations made by scientists with a zeal to invent new.

9th Class Physical Science 2nd Lesson Laws of Motion InText Questions and Answers

9th Class Physical Science Textbook Page No. 24

Question 1.
Do all the bodies have the same inertia?
Answer:
The inertia of all bodies is not same. It depends on the mass of the object.

Question 2.
What factors can decide the inertia of a body?
Answer:
Mass is the factor, which decides the inertia of a body.

9th Class Physical Science Textbook Page No. 26

Question 3.
Is the acceleration increased when net force is increased?
Answer:
Yes, the acceleration increased, as we increased the net force without changing mass of the object.

9th Class Physical Science Textbook Page No. 29

Question 4.
What do you notice from the readings in the spring balances?
Answer:
The two spring balances stretch up to a certain limit equally.

Question 5.
Are the readings of two spring balances the same?
Answer:
Yes, the readings of two spring balances are equal.

Question 6.
Are we able to make the spring balances to show different readings by pulling them simultaneously in opposite directions? Why not?
Answer:
When same force is applied in both the directions, we are unable to make the spring balances to show different readings because the action and reaction are same in magnitude and opposite in direction. When we use two forces with different magnitudes, then the spring balances can show different readings.

9th Class Physical Science Textbook Page No. 30

Question 7.
Does the rocket exert a force on the gas expelled from it?
Answer:
The rocket also exerts a force on the gas expelled from it.

9th Class Physical Science Textbook Page No. 32

Question 8.
Why does a pole vault jumper land on thick mats of foam?
Answer:
A thick mat of foam reduces the force of impact of the jumper, so that he doesn’t have any damage to his body.

Question 9.
Is it safe to jump on sand rather than a cement floor? Why?
Answer:

• It is safe to jump on sand rather than a cement floor.
• A soft and more cushioned landing surface provides a greater stopping distance because of the longer time taken to stop.

9th Class Physical Science Textbook Page No. 24

Question 10.
You may have seen the trick where a tablecloth is jerked from a table, leaving the dishes that were on the cloth nearly in their original positions.
a) What do you need to perform this successfully?
Answer:
We need a table, a cloth and some massive objects to perform this activity. The performer drag the cloth from the table very skillfully.

b) Which cloth should we use? Is it cloth made of thick cotton or thin silk?
Answer:
We have to use a thin silk cloth to perform this activity.

c) Should the dishes possess large mass or small mass?
Answer:
The dishes must possess large mass. We should not use lighter objects like plastic cups, etc.

d) Is it better to pull the cloth with a large force or pull it with a gentle and steady force?
Answer:
The cloth must be pulled with a gentle force, but with a sudden jerk.

Question 11.
What is the velocity of a small object that has separated from a rocket moving in free space with velocity 10 km/s?
Answer:
When a small object is separated from another object which is moving with a certain velocity. The small object also moves with a velocity equal to that of the object from which it is separated. Hence, the speed of the small object is 10 km/s.

9th Class Physical Science Textbook Page No. 27

Question 12.
Observe the following diagram.

What is the upper limit of weight that a strong man of mass 80 kg can lift as shown in figure?
Answer:
Total force mg = N + T (N = normal force, T = tension)
As the person is standing on the floor, the normal force N = 0.
80 = 0 + T
∴ T = 80
∴ The upper limit of the weight that the person in the figure can lift is 80 kg.

Question 13.
What is the momentum of a ceiling fan when it is rotating?
Answer:
Ceiling fan when it is rotating, possesses angular momentum.
Angular momentum L = mvr or mr²ω.

Question 14.
Is it possible to move in a curved path in the absence of a net force?
Answer:
A body comes into curved path, when centripetal force real force acts on it. Immediately after coming into curved path, an imaginary force which acts away from the centre i.e., centrifugal force comes into existence. These two forces are equal in magnitude and opposite in direction. Hence the net force is zero. So it is possible to move in a curved path in the absence of a net force.

Question 15.
Prove that the tension throughout the string is uniform when the mass of string is considered to be zero.
Answer:

Let a body of mass m is suspended through a string. The weight of the object mg acts downwards. Now tension in the string T = mg + m_sg when m_s is the mass of the string.
Here m_s is considered as zero.
Hence T_A= mg + 0 = mg; T_B = mg ; T_C = mg ; T_D = mg
∴ The tension throughout the string is uniform when the mass of string is considered to be zero.

9th Class Physical Science Textbook Page No. 31

Question 16.
The force exerted by the earth on the ball is 8 N. What is the force on the earth by the ball?
Answer:

• The force exerted by the earth on the ball is 8 N.
• The force exerted by the ball on the earth is – 8 N.

“According to Newton’s third law, if a body A exerted a force p on another body B, the B exerts a force -p on A, the two forces acting along the same line”.

Question 17.
A block is placed on the horizontal surface. There are two forces acting on the block. One, the downward pull of gravity and other a normal force acting on it. Are these forces equal and opposite? Do they form action – reaction pair? Discuss with your friends.
Answer:
These two forces form action-reaction pair.

Question 18.
Why is it difficult for a fire fighter to hold a hose that ejects large amount of water at high speed?
Answer:
A large amount of water with high speed ejects from the hose of a fire engine, produces a large force in forward direction. According to action-reaction, the hose moves back with the same force. But the fire fighter has to resist that reaction force. Hence it becomes very difficult for him.

9th Class Physical Science Textbook Page No. 33

Question 19.
A meteorite burns in the atmosphere before it reaches the earth’s surface. What happens to its momentum?
Answer:
The momentum of the meteorite becomes zero. It doesn’t touch the ground as it burns in the atmosphere. So no mass of the meteorite hits the ground.

Question 20.
As you throw a heavy ball upward, is there any change in the normal force on your feet?
Answer:
The normal force on the feet changes its direction and acts in upward direction. As a result we raise our foot while throwing the ball.

Question 21.
When a coconut falls from a tree and strikes the ground without bouncing. What happens to its momentum?
Answer:
Its momentum doesn’t change but its impact force will be very less because it is not bouncing.

Question 22.
Air bags are used in’the cars for safety. Why?
Answer:
When a car hits another vehicle, the air bags immediately comes in between the persons in the car and the wind shield of the car, to prevent damage to life of passengers.

9th Class Physical Science 2nd Lesson Laws of Motion Activities

Activity – 1

Question 1.
Explain the motion of a pen cap kept on a thick paper ring.
Answer:

1. Make a circular strip from a thick paper.
2. Balance the hoop on the centre of the mouth of the bottle.
3. Now balance a pen cap on the paper hoop aligning it on the centre of the bottle’s mouth.
4. Give the paper hoop a sharp push with your finger as fast as you can.
5. We observe that the pen cap suddenly falls into the bottle.
6. As we push paper hoop, we applied force on the paper hoop. So it changed its state from rest to motion.
7. Pen cap cannot change its state of rest.
8. Due to gravitational force, the pen cap falls into the bottle.

Activity – 2

Question 2.
Explain the motion of the carrom coins hit by a striker.
Answer:

1. Make a stack of carrom coins on the carrom board.
2. Give a sharp hit at the bottom of the stack with striker.
3. We can find that the bottom coin will be removed from the stack.
4. The other coins in the stack will slide down.
5. When we apply force on the bottom coin, the coin will move, due to change in the state of rest.
6. The stack of remaining coins does not fall vertically due to inertia.

Activity – 3

Question 3.
Show that the object with larger mass has greater inertia.
Answer:

1. Take two rectangular wooden blocks with different masses.
2. Place them on a straight line drawn on a floor.
3. Give the same push at the same time to both the blocks with the help of a wooden scale.
4. We observe that the block with small mass will accelerate more and goes farther.
5. The block with large mass accelerates less and moves shorter, due to high inertia.
6. This shows that the bodies of higher mass have high inertia.

Activity – 4

Question 4.
Show that the larger the net force greater the acceleration.
Answer:

1. Gently push a block of ice on a smooth surface and observe how the object speeds up, in other words how it accelerates.
2. Now increase the net force and observe change in its speed.

Observation : The acceleration increases.

Conclusion : If the net force is larger, then the accelerations greater.

Activity – 5

Question 5.
Show that the larger the mass smaller the acceleration.
Answer:

1. Apply a force on an ice block.
2. It undergoes some acceleration.
3. Now take a block of ice with greater mass.
4. Then apply almost the same force on the ice block which has greater mass.

Observations :

1. In both cases the object accelerates.
2. But we can observe in the second case, it will not speed up as quickly as before.

Conclusion : If the mass is larger, then the acceleration is smaller.

Activity – 6

Question 6.
Pulling two spring balances.
Answer:
Let’s take two spring balances of equal calibrations. Connect the two spring balances as shown in figure. Pull the spring balances in opposite directions as shown in figure.

Observation :
There is no change in the reading of spring balances. We are not able to make the spring balances to show different readings by pulling them simultaneously in opposite directions.

Conclusion :
According to third law of motion, when an object exerts a force on the other object, the second object also exerts a force on the first one which is equal in magnitude but opposite in direction.

The two opposing forces are known as action and reaction pair. Newton’s third law explains what happens when one object exerts a force on another object.

Activity – 7

Question 7.
Describe the preparation of a balloon rocket. What is the principle involved in it?
Answer:

Preparation of a balloon rocket :

1. Inflate a balloon and press its neck with fingers to prevent air escaping from it.
2. Pass a thread through a straw and tape the balloon on the straw.
3. Hold one end of the thread and ask your friend to hold the other end of the thread.
4. Now release air from balloon by removing fingers from the neck of the balloon.
5. The balloon moves like a rocket towards the other end

Principle involved in it:

1. Newton’s third law of motion is the principle.
2. As the air in the balloon moves backward, the balloon moves forward.

Lab Activity

Question 8.
Describe an activity to study the action and reaction forces acting on two different objects.
Answer:
Aim : To show the action and reaction forces acting on two different objects.

Material required : Test tube, rubber cork cap, Bunsen burner, laboratory stand and thread.

Procedure :

1. Take a test tube and put a small amount of water in it.
2. Place a rubber cork cap at its mouth to close it.
3. Now suspend the test tube horizontally to a stand with the help of two strings.
4. Heat the test tube with a bunsen burner until water vapourize and the rubber cork cap blows out.

Observations :

1. Observe the movement of test tube when cork cap blows out.
2. As the cork cap blows out in forward direction, the test tube recoils back.
3. We can observe the velocities of cork cap and recoil of test tube to be same.

Activity – 8

Question 9.
Show that the impulse will be less on a soft and cushioned surface.
Answer:

• Take two eggs.
• Drop them from a certain height, so that one egg falls on a concrete floor and the other on a cushioned pillow.
• We observe that the egg that falls on a concrete floor will break.

• The reason is large force acts on the egg for short interval of time.
  ∆p = F_net∆t
• The egg which falls on a cushioned pillow doesn’t break, because a smaller force acts on the egg for a longer time.
  ∆p= F_net ∆t
• This shows that the impulse (∆P) will be less on a soft and cushioned surface.

Note : Even if the ∆p is the same in both cases, the magnitude of the net force (F_{net</sub) acting on the egg determines whether the egg will break or not.}

AP State Syllabus AP Board 9th Class Social Studies Important Questions Chapter 10 Prices and Cost of Living.

AP State Syllabus 9th Class Social Studies Important Questions 10th Lesson Prices and Cost of Living

9th Class Social 10th Lesson Prices and Cost of Living 2 Marks Important Questions and Answers

Question 1.
“Public distribution system is one of the government programme to eradicate poverty. But one aspect of this programme is that it is not reaching the eligible people”.
Suggest the measures for better implementation of public distribution system? (SA-III : 2015-16)
Answer:
The following measures should be taken to improve the present Public Distribution System (PDS).

1. Implementation of measures such as door step delivery of food grains.
2. Improving viability of fair price shop operations.
3. Greater monitoring and vigilance.
4. Improve food grains off take.
5. Correct identification of beneficiaries.
6. Smart system communication like information provided to consumers by SMS about rations.

9th Class Social 10th Lesson Prices and Cost of Living Important Questions and Answers

Question 1.
What is inflation? Explain.
Answer:

• Continuous rise in prices of goods is known as inflation.
• The value of money also decreases with inflation.
• With more money also we could buy less goods only.
• This in turn increases the expenditure.
• Thus lower inflation is always better.

Question 2.
Who do you think are not affected by rising prices?
Answer:

• Not everyone is affected by rising prices.
• Extremely rich persons are not affected by rising prices.
• People those, who are working in corporate sector do not get affected by rising prices.

Question 3.
What is a price index? How is it useful?
Answer:

• Change in price is measured with the help of a statistical device referred to as price index.
• Change in prices of one good does not affect all goods and services in the same way.
• So we use index numbers of prices to measure the overall change in prices.
• Index numbers tell us about changes in the sum total of a set of items over time.

Question 4.
Read the following passage and answer the questions given below.

For preventing hoarding and keeping the prices of essential commodities within reasonable levels, and to facilitate their availability, the government fixes the prices and makes it mandatory for the traders to sell goods in the market at those price levels. Those who do not follow stipulated price levels are penalised by government through various laws. Goods such as kerosene, diesel, Liquid Petroleum Gas,- Compressed Natural Gas and Piped Natural Gas are examples of goods whose prices are partly or solely subsidised by the government and sold under Administrative Price Mechanism.

i) Why does the government fix prices under APM?
Answer:
For preventing hoarding and keeping the prices of essential commodities within reasonable levels and to facilitate their availability, the government fixes the prices.

ii) Which goods are subsidised by the government?
Answer:
Goods such as kerosene, diesel, liquid petroleum gas, compressed natural gas, piped natural gas are examples of goods which are partly or solely subsidised by the government.

Question 5.
Estimating Consumer Price Index
This is an example of how CPI can be constructed. Let us assume that your family buys rice, onions, dal, and gas cylinder.

1) How much more do we have to pay compared to last month?
Answer:
The expenditure has been increased by Rs. 350.

2) What is the percentage of increase?
Answer:
Percentage = \(\frac{350}{1500}\) × 100 = 23.3%

Question 6.
What is a budget? How does the government meet the deficit in the budget?
Answer:

• Budget is the financial statement which shows the anticipated incomes and expenditure of a family, or an institution or a state or any central government.
• When expenditures are more than incomes, then it is called a deficit budget.
• The government levies taxes on people to meet the deficit.

Question 7.
Nowadays there is rise in prices, why do people appear agitated and worried with it?
Answer:

• Nowadays rise in prices is common.
• People are always worried about rise in prices.
• It affects their consumption and they have to pay more for everything.
• Petrol prices increase, bus and auto fares increase, prices of groceries, vegetables, and milk increase, doctors fee increase and soon.
• Thus people always appear to be agitated about the rise in prices.

Question 8.
Prices of agricultural goods/products are volatile. What initiatives are taken by government to help farmers?
Answer:

• Government regulates traders in agricultural products/goods.
• It procures through Food Corporation of India, rice and wheat from farmers using Minimum Support Price (MSP).
• Traders also need to pay MSP.
• It also fixes price for sugarcane procured to make sugar in cooperative sugar mills.
• In these ways government try to regulate prices of agricultural products/goods in the market.

Question 9.
Why should the government give subsidies? On which items generally subsidies are given?
Answer:

• The government generally gives subsidies to keep the prices of essential commodities within the resonable levels.
• Goods such as kerosene, diesel, liquid petroleum gas, compressed natural gas, and piped natural gas are examples of goods whose prices are partly or solely subsidised by the government.

Question 10.
What measures are taken by government to control prices or reduce inflation?
Answer:

• To control unscrupulous rise in prices of essential goods in market, government supplies food items at subsidised prices through Public Distribution System.
• For preventing hoarding and keeping prices at reasonable level, government fixes prices of commodities like kerosene, diesel, gas, etc. through various laws.
• When there is price rise, RBI reduces the money circulation in the economy.
• Then it poses taxes on high-income groups and on many consumer goods.
• Government also uses Import – Export policy to regulate the prices of essential goods.
• Government also use legal mechanism whenever traders create shortage by hoarding.

SCERT AP Board 9th Class Social Solutions 2nd Lesson The Natural Realms of the Earth Textbook Questions and Answers.

AP State Syllabus 9th Class Social Studies Solutions 2nd Lesson The Natural Realms of the Earth

9th Class Social Studies 2nd Lesson The Natural Realms of the Earth Textbook Questions and Answers

Improve Your Learning

Question 1.
Fill in the blanks.
a) Hydrosphere is related to …………………….. .
b) Lithosphere is related to …………………….. .
c) Atmosphere is related to …………………….. .
d) Biosphere is related to …………………….. .
Answer:
a) water mass
b) land mass
c) air mass
d) life

Question 2.
Find the odd one out in the context of lithosphere and give reasons for your choice.
Byson gorge; Grand Canyon; Ozone; Thar desert.
Answer:
Out of these four ozone is the odd one.
Reasons:

1. Byson gorge and Grand canyon are hilly areas.
2. Rivers flow through them.
3. Plants and trees are present there.
4. Thar desert is a vast sand desert, with no water. It has thorny bushes and some kinds of desert plantations.
5. Above three are landforms.
6. But Ozone is an inorganic molecule with the chemical formula 03. It is a pale blue gas with a distinctively pungent smell. Ozone’s 03 formula was determined in 1865.

Question 3.
How is the Lithosphere formed?
Answer:

• The solid crust or the hard top part of the earth is called lithosphere.
• The crust is made up of rocks and minerals and covered with a thick layer of soil.
• It is uneven and has high mountains, plateaus, plains, and very deep basins.
• Many of these features are shaped by internal and external processes.
• The slow movements inside the earth lead to the formation of the crust.
• The sudden movements can damage and lead to changes in landforms.
• The processes originating from the depths of the earth like earthquakes and the volcanic eruptions play important role in shaping the surface of the earth.
• The external sources like wind, water, glaciers, and waves also play prominent role in shaping the lithosphere.

Question 4.
How are the continental plates formed and how are they eventually destroyed?
Answer:

• In the beginning, probably all continents were held together.
• Later the earth’s lithosphere is broken up into several pieces, just like the pieces of a large jigsaw puzzle and thus continental plates formed.
• These pieces, on which all the continents and oceans are actually situated, are called “Plates”.
• They float on soft layer of the mantle.
• There are about seven major plates and several minor plates on the earth.
• As the plates move, they push, pull, slide, rise, sink, bend and break.
• Sometimes one plate meets another, the incoming plate dips under the stable plate.
• In fact the incoming plate actually goes into the mantle of the earth and becomes molten due to the heat of the mantle.
• That is how some plates are eventually destroyed.

Question 5.
List out the landforms formed due to the river work. (AS1)
Answer:
Many landforms are formed due to the work of the river. They are
1. V – shaped valley:
The flow of a river is very swift as it descends the steep slopes and it exerts a great force in cutting the mountain vertically. As a result a deep valley develops, narrow at the bottom and wide at the top. This is called V – shaped valley.

2. Gorge:
Where the rocks are very hard, the river cuts a narrow valley with steep sides called Gorges.

3. Canyon:
A deep valley with steep like slopes and is wider at its top than at the bottom is called a Canyon.

4. A plunge pool:
The water falls with great force and dig out the rock beneath to form a plunge pool.

5. Plain:
When the river is in floods it cuts the soil and when it is not in flood it deposits silt and thus forms vast flood plains.

6. Meanders:
As a result of the deposition by floods the river bed becomes too high, the river constantly changes its course and cuts new path and forms gentle snake like meanders.

7. Ox-bow lakes:
Due to the deposition along the sides of the meanders, the ends of the meander loop comes closer and closer. In the course of time the meander loop cuts off from the river and forms a cut off lake which is called ox-bow lake.

8. Delta:
When a river reaches the sea, the fine material is deposited at its mouth forming a delta (∆).

9. Ozone:
Ozone is an inorganic molecule with the chemical formula 03. It is a pale blue gas with a distinctively pungent smell. Ozone’s 03 formula was determined in 1865.

Question 6.
Create a table as given below and fill information. And write a small paragraph to explain the similarities and differences you can think of in the context of earth’s external changes, (if there is no information available in the text, leave those columns blank)

	Wind	Water	Glacier
Landform
Process

Answer:
Wind:
Wind takes many forms and carries away the surface of the land in the higher places.

Water :

1. Water reacts with the chemicals of the rocks and further weakens the rock.
   Water acts as moving agent of the earth.

Glacier :

1. The ice on these glaciers melt throughout the year and flows to low areas as rivers and streams.
2. They also erode, transport and deposit rock materials.

Two forces, weathering and erosion, are constantly at work building up and moving rocks making up the earth’s crust.

Weathering causes rocks to fragment, crack, crumble, or break down physically and chemically.

Erosion loosens and carries away the rock debris formed by weathering. Over time these two forces, working together, change the shape of the land.

Question 7.
Why are Glaciers not found in your surroundings?
Answer:
Glaciers are most commonly found above snow line i.e., regions of high snow fall in winter and cool temperatures in summer. These conditions allow more snow to accumulate on the glacier in the winter that will melt in the summer. This is why most glaciers are found either in mountainous areas or the polar regions.

We are in the state of Andhra Pradesh. It is a semi-arid area and has a predominantly hot and dry climate. Summers start in March, and peak in May with average high temperatures in the 42°C range. A dry, mild winter starts in late November and lasts until early February with little humidity and average temperatures in the 22°C – 23°C range. In such hot and dry conditions glaciers are not formed. So we cannot find glaciers in our surroundings.

Question 8.
How are Beaches formed and name some Beaches?
Answer:
Formation of Beaches:

1. Sea water contains sediments like sand, pebbles, etc.
2. Beaches form as waves deposit these sediment on the shore.
3. The wind pushes these sediments on the shore and inland.
4. This creates an area of sand particles finally form a beach.

Names of some beaches :

1. Diu Beach
2. Manori Beach, Mumbai
3. Versova Beach, Mumbai
4. Mivamar Beach, Panaji
5. Karwar Beach, Karnataka
6. Fort Kochi, Cochin
7. Kovalam Beach, Trivandrum
8. Marina Beach, Chennai
9. R.K. Beach, Visakhapatnam
10. Chandipur Beach, Odisha.

Question 9.
How is the human lifestyle responsible for extension of deserts?
Answer:

• Desertification can be considered as a set of biological, chemical, and physical processes which converge to create desert-like conditions.
• Desertification is a social problem involving people at all stages as a cause and as victims.
• The anthropogenic (human) causes of desertification are over cultivation, over grazing, deforestation and poor irrigation practices.
• These factors are fuelled by local forces such as poverty and population pressure.
• Increase in temperature leads to drying out of water and it further causes to expansion of deserts.
• Mismanagement of dry land ecosystems by humans can cause desertification.
• Poor land use and overgrazing are significant factors for the expansion of deserts.
• Thus activities of human beings lead to the extension of deserts.

Question 10.
Find out the order of the landforms for the following.

Landform	Order of Landform
The Himalayan Mountains	II order Landform
The Pacific Ocean
Asia Continent
Byson Gorge
Jog waterfall
Rocky mountains
The Indian Ocean
The great rift valley

Answer:

Landform	Order of Landform
The Himalayan Mountains	II order Landform
The Pacific Ocean	1 order Landform
Asia Continent	1 order Landform
Byson Gorge	III order Landform
Jog waterfall	III order Landform
Rocky mountains	II order Landform
The Indian Ocean	1 order Landform
The great rift valley	III order Landform

Question 11.
Draw the map of world plates by observing map 2.
Answer:

Question 12.
Read the para under the title ‘Erosion’ on page 20 and comment on it.

Erosion : Flowing water and wind have great power and can slowly wear away or cut away the rocks and soil cover in higher places. Water acts in many ways, as rain, river, flowing ground water, sea waves, glaciers etc. Wind too takes many forms like storms, gusts, steady winds, etc. The active wearing away of the earth’s surface by these moving agents is called erosion.

Answer:
Erosion is the process by which soil and rock are removed from the earth’s surface by exogenic processes such as wind or water flow, and then transported andsdeposited on their locations while erosion is a natural process. Human activities have increased by 10 – 40 times the rate of which erosion is occuring globally.

Question 13.
Collect newspaper or magazine articles and news on earthquakes and volcanoes.
Prepare an illustrated file on these – how do they happen and how they affect human life.
Answer:
Student’s activity.
Ex: Earthquakes:
The earth’s surface is formed of massive slabs of rock called plates. These are called tectonic plates, are always moving. Sometimes they just slide past one another. At another time they actually collide with one another. Plate movements cause the build up of tremendous quantities of energy in the rock. When the energy is released, it produces vibrations that travel through the rock, leading to earthquakes. During earthquakes, faults, or giant cracks, are produced by the pressure of moving rocks.

Volcanoes:
Deep within the earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Because it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually some of the magma pushes through vents and fissures in the earth’s surface. Then a volcanic eruption occurs.

Their effect on human life :

1. Major earthquakes and volcano eruption can affect human life.
2. Roads can be damaged and delivery of food can be disrupted.
3. Clean, drinking water may not be available.
4. Sewer system may leave, causing diseases.
5. Gas line could leak, causing health issue.
6. All the surroundings can get covered with ash.
7. Communication system fails.
8. They destroy property and threaten human lives.

9th Class Social Studies 2nd Lesson The Natural Realms of the Earth InText Questions and Answers

Question 1.
Why do you think the rock is harder inside than outside? (Text Book Page No. 20)
Answer:

• The gradual disintegration of rocks is caused by atmosphere forces.
• The rocks when exposed to heat expand and contract when cooled down.
• As surface rock contracts and expands and contracts again, it gradually becomes brittle and begins to break down.
• Water reacts with the chemicals in the rock and further weakens it.
• These processes by which the rocks are weakened and broken are called ‘weathering’.
• It is easier to chip small pieces of rock from the outer layer rather than from the core of the rock.
• Thus we can say the rocks are harder inside than outside.

Question 2.
Expalin how are the waterfalls are useful. (Text Book Page No. 22)
Answer:

• The most noted advantage of waterfalls is their ability to produce hydroelectric power.
• As it descends the steep slopes the waterfall exerts a great force and cuts mountains vertically and forms V-shaped valleys, gorges and canyons.
• These attract many tourists throughout the world and earn a lot of foreign exchange.
• Waterfalls put oxygen into the water which first helps the fish breathe well.

Question 3.
Can you discuss in the class how the following human actions impact the lithosphere?
i) Mining
ii) Building cities with bricks and cement
iii) Agriculture
iv) Dams (Text Book Page No. 25)
(OR)
‘Human actions like mining, building cities with bricks and cement, agriculture and dams are impacting the lithosphere’ – Comment on it. Mra
Answer:
i) Impact of mining on lithosphere :

• Mining disturbs and removes the rocks, ores and minerals in the geosphere.
• It leaves huge gaping holes in the earth.
• The mine tailings are pulled up in large mounds on the surface of the geosphere.
• Subsidence is an effect that occurs above a deep mine.
• The deep mines cause redistribution of the existing tectonic stress field disturbed by the excavation process.
• High stresses exist inside tectonic plates and they are sensitive to any perturbations.
• In case of mining the mass removal causes fault zones and eventually earthquakes.

ii) Impact of building cities with brick and cement on lithosphere:
Constructing buildings with cement and bricks has a lot of negative effects.

• Concrete used to create hard surfaces causes to surface turn off and it can cause heavy soil erosion.
• Constructing the buildings with cement, bricks and concrete have different thermal and hydrological properties. These cause the surface absorbs and stores heat and water.

iii) Impact of agriculture on lithosphere:
Man has been trying to manipulate more and more of nature and exploit this natural resource by the unscientific practice of agriculture.

• Agriculture causes the depletion of underground acquifiers through overdrafting.
• Under irrigation gives poor soil salinity control which leads to increase soil salinity with consequent build up of toxic salts on soil surface.
• Wide use of agricultural chemicals causes soil pollution.

iv) Impact of dams on lithosphere :

• As a result of dam construction and holding of sediments in reservoirs sediment feeding of down stream channel or shore beaches is prevented.
• Corrosions may occur.
• Rare archaeological and historical places with their exceptional beauties disppear after lying under the reservoir.
• Earthquakes and volcanic activity can be induced by the weight of the reservoir on nearby faulty lines.
• Soil erosion of silt deposited at the edges of reservoirs can seriously damage surrounding vegetation and farmland by sand blow.

Question 4.
Write an imaginary description of the damages that occur due to volcanic eruption in an area. (Text Book Page No. 19)
Answer:

• Volcanic eruption can cause earthquakes, fast floods, mudslides and rock falls.
• Lava can travel very far and burn, bury or damage anything in its path including people, houses and trees.
• The large amount of dust and ash can cause roofs to fall, makes it hard to breathe and is normally very smelly.
• The ground around volcano is not secure and can cause big earthquakes.
• Big volcanic eruptions can change the weather around the world.
• Ash clouds float very high in the air and can cause snow and frost in the summer in a lot of countries.

Question 5.
Compare the Loess Plains with a Delta. What similarities and differences do you see between them? (Text Book Page No. 25)
Answer:
Similarities between Loess Plains and Deltas :

1. Both are the deposits of erosional fine materials on plains.
2. Both loess plains and deltas are fertile lands.

Differences between Loess Plains and Deltas:

1. While loess plains are formed with fine dust blown beyond the deserts, the deltas are formed with fine alluvial material transported by the rivers.
2. While loess plains are formed in the neighbouring lands of the deserts, the deltas are formed at the mouths of the rivers.
3. While loess are fine loam, rich in lime, very coherent and extremely porous, the deltas consist of clayey alluvial soils with a mixture of organic material.
4. While deltas are formed by the action of rivers, the loess plains are formed by the action of winds.

Question 6.
Geologists have found fossils of sea animals on the Himalayas. Some of these are actually worshipped in many homes as ’Salagramas’. How do you think are these^ossil^here on the Himalayas? (Text Book Page No. 17)
Answer:

• The Himalayas are formed by the collision of the Indian and Eurasian land masses which were originally separate.
• This collision uplifts mountains.
• From around 200 million years ago the area between the two separate land masses was covered by the Tethys sea, which was filling with sediments and had sea creatures which left fossils in the sedimentary rocks formed there.
• So the fossils found in the Himalayas are those formed in the ancient sea bed of the Tethys sea, now exposed and pushed up to form mountains.
• Salagramas are usually black coloured spherical fossils found in the sacred river Gandaki.
• The name salagrama refers to the name of the village on the bank of the Gandaki, where the holy stones are picked up.
• Hindus consider these salagramas as an iconic representation of Vishnu and worship these salagramas.

Question 7.
Collect information about the waterfalls in Andhra Pradesh. (Text Book Page No. 22)
Answer:
Waterfalls of Telangana :

1. Ethipothala falls, near Nagarjuna Sagar Dam.
2. Katiki waterfalls – Visakhapatnam district
3. Kailasakona falls – Chittoor district
4. Mallelatheertham – Nallamala forest, Kurnool district
5. Penchalakona falls – Nellore district
6. Rampachodavaram – East Godavari district
7. Talakona falls – Chittoor district
8. Ubbalamadugu or Tada falls – Chittoor district

Question 8.
Collect some of the pictures of waterfalls. (Text Book Page No. 22)
Answer:
Pictures of famous waterfalls :

Question 9.
Gorges are suitable for construction of dams- can you tell why this is so? (Text Book Page No. 21)
Answer:

• Gorges are narrow valleys with steep sides.
• A gorge is almost equal in width at its top as well as its bottom.
• They are suitable for the construction of massive reservoirs.
• The natural valleys formed by the gorges are built up with hard rock.
• The valleys with its steep sides, extensive rocky floors form the natural reservoirs for the dams.
• Constructing the dams at gorges is less expensive because a little concrete work is needed to form the reservoirs.
• In these vast and massive reservoirs a lot of water can be stored.
• Gorges are flood proof. They prevent floods.
• The waterfalls that falls down from great heights into the gorges can rotate large turbines and generate hydroelectricity in large quantities.
• Thus gorges are suitable for the construction of dams.

Question 10.
You have read about mining of minerals like baryte or coal. In what ways do you think does mining affects the lithosphere, hydrosphere and atmosphere? (Text Book Page No. 14)
Answer:

• Mining disturbs and removes the rocks, ores and minerals in the lithosphere leaving huge gaping holes in the earth.
• The mine tailings are piled up in large mounds on the surface of the earth.
• Mining waste when washed into the water ways pollutes the hydrosphere.
• Mining causes air pollution to the atmosphere in several ways.
• The mine might also release poisonous gases that were trapped below the surface.
• Mining affects the biosphere by affecting the other three spheres in an indirect way.

Question 11.
Human beings consume a lot of medicines like anti-biotics to cure sickness. How do you think does it affect the lithosphere, hydrosphere and biosphere? (Text Book Page No. 14)
Answer:

• More than 10,000 tonnes of anti biotics are consumed in Europe each year.
• 30%-60% of them passthrough animals and humans unchanged and reach the ocean.
• These antibiotics can affect the marine ecosystems over a long period, with detrimental effects on natural marine communities of bacteria.
• The presence of antibiotics in the marine environment is worrying as it can reach to humans through the consumption of sea food and fish.
• The marine sediments affected by the antibiotics metabolise both nitrogen and carbon which are linked to both eutrophication and climate problems.

Question 12.
What are the dangers of living on the flood plains? (Text Book Page No. 23)
Answer:

• Flood plains are flood prone areas.
• Massive damage can occur during floods in flood plains.
• Homes, automobiles, buildings, historical monuments, graves, sewer systems, bridges and countless other infrastructure can be destroyed.
• Road ways often suffer. High flooding often claims the lives of drowning victims.
• In flood plains during floods there will be lack of clean drinking water which causes illness and epidemics to spread.
• Thus there are a lot of dangers of living on the flood plains.

Question 13.
Locate the Himalayas, Andes and Rockies mountains. Why were they formed in those locations? Suggest reasons. (Text Book Page No. 17)
Answer:

1) Himalayas
2) Rockies mountains
3) Andes mountains

Reasons:

1. Fold mountains are mountains formed from the folding of the earth’s crust.
2. The Himalayas, the Andes and the Rockies are fold mountains.
3. These fold mountains are formed when two plates move together.
4. The Himalayan mountains were formed by the process of Indian plate pushing the Eurasian plate.
5. The forces of plate tectonics are responsible for the formation of Andes.
6. The Nazce plate and a part of the Antarctica plate have been subducting beneath the South American plate.
7. The Rockey mountains took shape during an intense period of plate tectonic activity that resulted in much of the rugged landscape of the Western North America.
8. The Laramide Orogeny was responsible for raising the Rocky mountains.

Question 14.
You may have noticed that many of the ‘scientific’ terms use Greek words. Why do you think do they use Greek words? Discuss with your teacher. (Text Book Page No. 14)
Answer:
In his communication a scientist is mainly concerned with exact and logical expression of that which he wishes to pass on to another. His purpose is to inform as clearly as possible. Each of his words must have a precise meaning and one meaning only so that there is no risk of confusion or ambiguity. The meanings of many ordinary words of our language are not single and precise. The use of words which are ‘set apart’ from everyday life also enables the scientist to avoid evoking irrelevant and distorting associations.

In addition to precision of meaning and freedom from associations most scientific words by their form and structure they reveal something of their meanings. Many scientific words are built from simpler word-elements usually of Greek origin. Some words are self-explanatory if the Greek roots are known.

Scientific language to be efficient must be universally intelligible. The classical language Greek is so fundamental to the civilised world. The words constructed from this language can easily be learnt to be translated.

So scientific terms use Greek words.

Question 14.
Are all rocks on the earth formed in the mid-ocean ridges? (Text Book Page No. 17)
Answer:
No. All the rocks on the earth are not formed in the mid-ocean ridges. Only ocean rocks or crust are formed of the mid-ocean ridges. These are formed by lava rising up from the mantle. The eruptions on the ridges create new ocean floor made of basalt rocks, which then spreads laterally from the ridge. The first order landforms such as oceans and continents are formed at the time when the hot earth was cooling. While the earth’s interior continued to cool, it contracted and the outer crust wrinkled forming ridges i.e., mountains and basins i.e., oceans. The second order landforms such as plains, plateaus and mountains are formed as a result of the internal processes of the earth. The third order landforms such as carved mountains, valleys, deltas, sand dunes are formed as a result of the shaping of the land forms by wind, water.

Question 15.
Why do you think we don’t feel any of these mighty changes taking place on the earth? Is it because they don’t affect us? Do you think these changes affect us at all? (Text Book Page No. 17)
Answer:

• Two kinds of changes take place in the Lithosphere – first the very slow movements leading to the formation of the crust, movement of the continental plates and their eventual return to the mantle.
• Since these geophysical changes occur over thousands and even millions of years we don’t feel any of these changes.
• Secondly the sudden and dramatic eruption of volcanoes and earthquakes.
• The sudden movements can be destructive and cause much damage. At the same time they also lead to changes in landforms.

Question 16.
Compare the action of the river in the mountains and in the plains. In what ways are they similar and different?
Answer:
Similarities :

1. They carry something when they flow across the two landforms.
2. They have streams in both the areas.
3. They change the surface of the earth.

Differences

In the mountains	In the plains
1. Rivers originate in mountains.	1. Rivers run and flow across the plains.
2. They flow very fast.	2. They flow slowly.
3. They carry the rocks.	3. They deposit the sediments here.
4. They form gorges and canyons here.	4. They form deltas here.

From the mountains to delta, a river does not just flow – it changes the surface of the earth.

It cuts rocks, moves boulders, and deposits sediments.
It constantly attempts to carve away all the mountains in its path.

The goal of the river is to create a wide, flat valley which it can flow smoothly towards the ocean.

That is the relation between the mountains and plains.

Question 17.
Why is a flood plain more suited to human habitation compared to mountains? (Text Book Page No. 23)
Answer:
Disadvantages of mountains :

1. High elevation on mountains produces colder climates than at sea level.
2. These colder climates strongly affect the human habitation.
3. Climate of mountains to be used less for agriculture.
4. Abundant water supply.
5. Fertile land – rich for farming and agriculture.
6. Easy to develop than hilly regions.
7. Flood water can be stored temporarily.
8. Many civilizations are flourished on the banks of the rivers.
   These are all more suited to human habitation compared to mountains.

Question 18.
Recall the life of people living in the hills or flood plains that you may have read of. (Text Book Page No. 23)
Answer:
Bison hills are spread in both Bhadradri Kothagudem and W. Godavari districts along either banks of the river Godavari. Many tribal communities live in the hill tracts of this region with their own special life.

These tribals live in small habitations – about 5 to 10 hutments in one place. The habitations are far from each other.

Konda Reddys grow crops in a distinct way called Podu. When rains arrive in June they dibble seeds with the help of digging seeds.

Except for a few months during and after harvest, Konda Reddy women and children are engaged in collection of edible forest produce for subsistence.

There are no rivers or wells in this area. They fetch water from natural springs.

These hill tribes are very few in number but they follow a pattern of life which is very ancient.