NCERT Solutions for Class 7 Science Chapter 16 Water – A Precious Resource

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)

Answer: True.

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

Answer: False.

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

Answer: False.

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

Answer: True.

2. Explain how groundwater is recharged?

Answer: By the process of infiltration groundwater gets recharged. During infiltration, water from surface, rivers or lakes seeps from cracks and spaces, deep into the soil.

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

Answer: If water from ten tube wells is used by fifty houses, then continuous use for long time will reduce water level, thus, water table will go down.

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

Answer: For maintaining a garden, there is large amount of water required. Therefore, to minimise use of water drip irrigation should be use. In drip irrigation, water is provided drop by drop to the base of the plants using narrow tubes.

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

Answer: Following are some factors responsible for depletion of water table-

• Population growth: Due to growth in population, demand of water increases.
• Growth in industries: in manufacturing process water is required. If industries increases then requirement of water also increases.
• Agricultural activities: Water requirements during agriculture is fulfilled from rain water, canals, rivers or groundwater. Water from rainfall is not available throughout the year. Also, canals or river water is not available in all places. Therefore, groundwater is main source of water which is used for agriculture. Thus, it decreases water table.

6. Fill in the blanks with the appropriate answers:

(a) People obtain groundwater through________ and ________.

Answer: handpump, tube well

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

Answer: vapour, water, ice

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

Answer: aquifer

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

Answer: infiltration

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 rainfall

8. Choose the correct option. 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: of the world remains constant.

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

Answer:

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