AP State Syllabus AP Board 7th Class Science Important Questions Chapter 14 Water – Too Little To Waste
AP State Syllabus 7th Class Science Important Questions 14th Lesson Water – Too Little To Waste
7th Class Science 14th Lesson Water – Too Little To Waste Important Questions and Answers
How is water distributed on the globe? How much of freshwater is available to us?
- If the total water on earth be 100%, the percent fresh water available to us is only 1%.
When was the international decade for action on ‘water for life’ declared?
- On World Water Day, that is 22 March 2005, the period 2005 – 2015 was declared as the International Decade for action on “Water for Life”.
What would you do for the cause ‘water for life”?
- Normally a lot of water flows out of the kitchen as well as bathrooms in our houses.
- Many of us do not know that water is being wasted in this way.
- We must make a channel of water to flow from kitchen to the garden around.
- We cannot wastewater from the bathroom also. It could be used after purification.
Why do we need proper drainage system?
- We dispose of wastewater in our daily life in different ways and means.
- We often see water stagnated near bore wells or beside houses.
- Sometimes human and animal excretions also mix with this water.
- We get a foul smell when we walk near those areas.
- To prevent this we need a proper drainage system.
How do you find out what realty happens to waste water at treatment plants?
- Fill a large glass jar 3/4 full of water. Add some dirty organic matter such as grass pieces or orange peels, a small amount of detergent, and a few drops of an ink or any colour.
- Cap the jar, shake it well and let the mixture stand in the sun for two days.
- After two days, shake the mixture and pour a small sample into test tube. Label this test tube “Before treatment; Sample 1”. How does it smell?
- Use an aerator from an aquarium to bubble air through the sample in the glass jar. Allow several hours for aeration; leave the aerator attached overnight. If you do not have an aerator, use a mechanical stirrer or a mixer. You may have to stir it several times. This actually works like a skimmer of the wastewater treatment plant.
- Aeration causes organisms that break down waste to grow faster thus it leads to what is called as “Biological Process”.
- The next day when aeration is complete, pour another sample into a second test tube. Label it “After aeration; Sample 2”.
- Fold a piece of filter paper to form a cone. Wet the paper with tap water and then insert the cone in a funnel. Mount the funnel on a support.
- Place layers of sand, fine gravel and finally medium gravel in the funnel.
- Pour the remaining aerated liquid through the filter into the beakers. Do not allow the liquid to spill over the filter. If the filtered liquid is not clear, filter it a few times till you get clear water. This is “physical process”.
- Pour a sample of the filtered water into a third test tube labeled “Filtered’ Sample 3”.
- Pour another sample of the filtered water into a fourth test tube. Add a small piece of a chlorine tablet. Mix well until the water is clear. Labe! the test tube “Chlorinated; Sample 4”.
- This is a “Chemical Process” of treatment.
- Observe carefully the samples in all the test tubes. Do not taste! Just smell them!
- We can easily under stand how the wastewater is recycled in the treatment plant.
For which purposes are we using freshwater?
Answer: Freshwater has been the constant and essential companion of human beings throughout history. Water is used in great quantities in agriculture and industries.
How is freshwater distributed over the globe?
- Our globe is poorly endowed with fresh water.
- Most water is rendered useless to humans by dilution with salt in the oceans.
- Only 2.5 percent is available as freshwater of which 2/3 is locked up in Ice and snow.
- Nature is unkind in depositing almost eighty percent of rain over the sea.
- The rain that falls over the land has a great potential value.
What is causing water scarcity? Write the principle ways which are degrading the quality and quantity of natural supply of fresh water.
- Unsustainable extraction of fresh water causes water scarcity.
- Due to the over-extraction of fresh water underground reserves are falling rapidly.
- In India, the water table has fallen more than 300 meters’.
- Human interventions which degrade the quality and quantity of the natural supply of fresh water occur, in 3 principal ways.
- Firstly dams alter the natural flow of rivers often leading to water scarcity.
- Secondly, soil moisture is lost by land degradation due to poor farming practices
- Thirdly, surface water is polluted by run-off chemicals used in industries and households.
How can you say that the next cold war could be over water?
- The world population is projected to grown 9.3 Billion by 2050.
- In addition to safe drinking water and sanitation, the rising pressure on freshwater will be felt most severely in the energy and food sectors.
- Two out of three people will be living with water shortage by 2025.
- The growth of demand the decline in freshwater availability, the adverse health effects from poor water quality and scarcity will result in violence and water wars.
- The next cold war could be over water.
How can we conserve water? Write some practices that can be adopted.
- We perform many activities in our daily life using water.
- We can conserve water by adopting certain good practices,
b) Some practices that can be adopted:
- Water is precious. We should not waste it.
- Collect water in a bucket after cleaning rice, dal and vegetables in the kitchen which contains peels of vegetables.
- We can use this water for our cattle.
- We should not throw solid food remains, tea leaves and oily wastes down the drain.
- We must make a channel so that the kitchen and bathroom water flows to the coconut and banana plants in our garden.
- We should use only mild soaps and detergents so that this water may not harm our plants.
- Any leakage of water from any tap must be repaired immediately.