16. Water : A Precious Resource Science class 7 in English Medium ncert book solutions NCERT Exercise

Exercise 

1. Mark ‘T’ if the statement is true and ‘F’ if it is false:

(a) The freshwater stored in the ground is much more than that present in the rivers and lakes of the world. (T/F)

(b) Water shortage is a problem faced only by people living in rural areas. (T/F)

(c) Water from rivers is the only source for irrigation in the fields. (T/F)

(d) Rain is the ultimate source of water. (T/F)

Answer:

(a) T  (b) F  (c) F  (d) T

2. Explain how groundwater is recharged?

Answer:

The rain water and water from other sources such as river and ponds seeps through the soil and fills the empty spaces and cracks deep below the ground. The process of seeping of water into the ground is called infiltration. The groundwater thus gets recharged by this process.

3. There are ten tubewells in a lane of fifty houses. What could be the long term impact on the water table?

Answer:

The water table will be depleted. Atime will come when table fall below the pipe of tubewells. Water will not be fetched by these any more. 

4. You have been asked to maintain a garden. How will you minimise the use of water?

Answer:

(i) By collecting rain water.

(ii)By using water after bath or washing utensils for watering in the garden.  

5. Explain the factors responsible for the depletion of water lable.

Answer:

(i) Increasing population: Increasing population creates demand for construction of houses, shops, offices, roads and pavements. This decrease the open areas likeparks, and playground.

(ii) Increasing industries: Water is used by all the industries. The number of industries is increasing continously. Water used by most of the industries is drawn from the ground

(iii) Agriculture activities: These irrigation system may suffer from lack of water due to erractic rainfall. Therefore, farmers have to use groundwater for irrigation.  

6. Fill in the blanks with the appropriate answers:

(a) People obtain groundwater through________ and ________.  

(b) Three forms of water are ________, ________ and ________.

(c) The water bearing layer of the earth is ________.

(d) The process of water seepage into the ground is called ________.

Answer:

(a) well and hand pumps (b) solid, liquid and gas (c) acquifer (d) infirltration.

7. Which one of the following is not responsbile for water shortage? 

(i) Rapid growth of industries

(ii) Increasing population

(iii) Heavy rainfall

(iv) Mismanagement of water resources 

Answer:

(iii) Heavy rainfall.

8. Choose the correct opton.

The total water

(i) in the lakes and rivers of the world remains constant.

(ii) under the ground remains constant.

(iii) in the seas and oceans of the world remains constant.

(iv) of the world remains constant.

Answer:

(iv) Of the world remains constant.

9. Make a sketch showing groundwater and water table. Label it.

Answer-

Groundwater and Water lable