Water A Precious Resource - Solutions

 CBSE Class–VII Science

NCERT Solutions

Question 1. Mark “T” if the statement is true and ‘F” if it is false:

(a) The fresh water 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

Question 2. Explain how groundwater is recharged?

Answer: The rainwater and water from other sources such as rivers and ponds etc 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 is recharged through this process.

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

Answer: This will lead to exploitation of water resource present underground if people of all the fifty houses in the lane use the ten tubewells regularly. In long term, the water level will go
below and thus the depletion of tubewells.

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

Answer: For minimising the use of water in maintenance of garden, i will use the technique of drip irrigation. In this method, required amount water is supplied directly to the roots of the plants
using narrow pipes thus preventing the loss of water.

Question 5. Explain the factors responsible for the depletion of water table.

Answer: Factors responsible for the depletion of water level:
(i) Increase in the demand of water due to overpopulation.
(ii) Deforestation leads to less rainfall which affect the recharge of river and pounds.
(iii) Increase the number of industries as they use a lot of water for their purpose.
(iv) Insignificant uses in agriculture activities as in many parts of the world people uses old techniques which waste a lot of water.
(v) Lack awareness in people is also a main reason behind the depletion of water level as they waste water without any uses.

Question 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: Fill in the blanks.

(a) People obtain groundwater through well and hand pump.

(b) Three forms of water are icewater and (water) vapour.

(c) The water bearing layer of the earth is aquifer

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

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

(i) Rapid growth of industries.

(ii) Increasing population

(iii) Heavy rainfall

(iv) Mismanagement of water resources.

Answer: (iii) heavy rain.

Question 8. Choose the correct option. The total water

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

(ii) Under the ground remain 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.

Question 9. Make a sketch showing ground water and water table. Label it.