Chapter 16: Water - A Precious Resource

  Science

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  Chapter 16: Water - A Precious Resource

   Class: VII

  NCERT Questions

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. By the process of infiltration, groundwater gets recharged.

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 tube-wells are too much for a lane of fifty houses, this can lead people to mindlessly exploit the groundwater. This can lead to depletion of the water table in the long run.

Question 4

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

Answer 4

Drip irrigation and sprinklers system can be used in the garden to minimize the use of water. Watering to plants should be done to minimise loss of water by evaporation.

Question 5

Explain the factors responsible for the depletion of water table. 

Answer 5

Following factors are responsible for depletion of water table:  There is more demand of water due to increasing population. Which lead to increasing demand of water for various human activities.   Deforestation has removed a large portion of forest cover. This has disturbed the natural process of recharging the groundwater. Demand for water has increased and the recharging of the ground water has reduced. The mismatch between demand and supply is mainly responsible for depletion of water table.

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 tubewells. (b) Three forms of water are solid, liquid and gas. (c) The water bearing layer of the earth is water table. (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

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