Page 163 - Science Class 07

i Rain harvesting is a method used to recharge ground water.

i Sedimentation, decantation, filtration, etc. are the methods used to purify water.

Ex
Exercise
Ex
Exerciseerciseerciseerciseerciseercise
Ex
Ex
Ex
A. Tick (3) the correct op on.
1. How much water does our body cons tute?
(a) 50% (b) 100%
(c) 65% (d) 85%
2. How much of total water is salty?

(a) 82.5% (b) 97.2%
(c) 67.5% (d) 37.7%
3. How much of the total water is potable?
(a) Less than 1% (b) More than 1%

(c) 1% (d) None of these
4. Rain water harves ng is a method to:
(a) store rain water in tanks (b) use rain water for irriga on
(c) recharge groundwater (d) none of these

B. Fill in the blanks.
1. The two elements that cons tute water are ___________ and ___________ .
2. Water helps the bodies of animals to maintain the ___________ needed by them.

3. Agricultural produc on depends on the availability of ___________ .
4. In thermal power plants, ___________ is used to rotate the turbines.
5. The amount of fresh water is reducing day-by-day due to ___________ .
6. _________ irriga on must be encouraged so as to check percola on of harmful chemicals.

C. Write True or False.
1. Aqua c animals take in oxygen dissolved in water.
2. Water is necessary for agricultural as well as industrial development.

3. In hydroelectric plant, steam is used to rotate turbines.
4. Earth has as much water on it as it had millions of years ago.
5. Germs from filth and dung enter water and pollute it.
D. Very short answer ques ons.
1. Write any three domes c uses of water.

2. Write any three industrial uses of water.
3. What is the importance of water in our body?
4. How much of total water is potable water?
5. What is water pollu on?

6. What do you mean by potable water?

Science-7 163