Chapter 16 Water : A Precious Resource

By | March 16, 2019

Class 7 | Science | Chapter 16 | Water : A Precious Resource | NCERT Solutions

Question 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 1 (a) The freshwater stored in the ground is much more than that present in the rivers and lakes of the world: (T)
(b) Water shortage is a problem faced only by people living in rural areas: (F)
(c) Water from rivers is the only source for irrigation in the fields:(F)
(d) Rain is the ultimate source of water: (T)

Question 2. Explain how groundwater is recharged?

Answer 2 The rainwater and water from other sources such as rivers 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.

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

Answer 3 Ten tubewells are too much in a lane of fifty houses , this can lead people to exploit the groundwater. If there is shortage of rains, the water used by the family will not replenished and water table will fall down.

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

Answer 4 To minimise the wastage of water we will use the drip irrigation which throws the water at the base of plants. We will check the leakages in the water pipes and arrange small pits for rainwater harvesting.

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

Answer 5 Various factors responsible for the depletion of water table are:

(i) Increased population: Demand of water has been increased by the increased population. As the number of humans increase, the consumption of water also increases.

(ii) Increasing industries: As the number of human population increase, the number of industries are also increased which definitely increases the consumption of water.

(iii) Lack of water conservation techniques: Main source of water on earth and for the underground water is rain. The water of the rain, if conserved can increase the ground water level. But this is not done due to lack of water conservative techniques.

(iv) Agricultural activities: India is a country which depends on agriculture. The land used for cultivation has increased. So, the consumption of water for agriculture has increased. Irregular rainfall has increased the consumption of groundwater. This has increased the depletion of groundwater.

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 6

(a) People obtain groundwater through wells and hand pumps.
(b) Three forms of water are solid , liquid and gas.
(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 7 (iii) Heavy rainfall

Question 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 8 (iv) of the world remains constant.

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

Answer 9

Groundwater and water table

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