NCERT Solutions of Chapter: Water: A Precious Resource. NCERT Solutions along with worksheets and notes for Class 7.
(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.
(b) Water shortage is a problem faced only by people living in rural areas.
(c) Water from rivers is the only source for irrigation in the fields.
(d) Rain is the ultimate source of water.
Ans-
(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. F
(2) Explain how ground water is recharged?
Ans-Rain water and water from other resources such as river, ponds etc get infiltrated into the soil. From there it reached to water table and aquifer and ground water get recharged through seeping and infiltration.
(3) There are ten tubewells in a lane of fifty houses. What could be the long term impact on the water table?
Ans- Water level of water table will decrease in the long term if fifty houses use water from tubewells. If infiltration of water from rain and other resources continuously happen only then water level in water table stand stable.
(4) You have been asked to maintain a garden. How will you minimise the use of water?
Ans- I will use rain harvesting and drip irrigation method for watering the plants of my garden. It will minimise the use of water.
(5) Explain the factors responsible for the depletion of water table.
Ans- The factors responsible for the depletion of water table are given below:
(i) Increase in population creates demand for more houses, shops, offices etc. Increase in construction decreases open areas like parks, playgrounds. It leads to decrease in seepage of rainwater.
In spite of this, huge amount of water is needed for construction which is often taken from groundwater. So, we are fetching more ground water and allowing less seep into the ground. Level of water in water tables are depleting continuously.
(ii)The number of industries is increasing continuously. Every industry needs water for production. Most of the industries use ground water. So, ground water level is decreasing rapidly.
(iii)Farmers depend on rainfall for irrigation. Due to erratic rainfall canals suffer lack of water. Irrigation system is not available in all over India. So, farmers have to draw ground water for irrigation. This results in depletion of water table.
(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 processes of water seepage into the ground is called______.
Ans-
(a) People obtain groundwater through tube wells and hand pumps.
(b)Three forms of water are solid, liquid and gaseous.
(c) The water bearing layer of the earth is aquifer.
(d) The processes of water seepage into the ground is called 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
Ans-
(i) Rapid growth of industries
(ii) Increasing population
(iii) Heavy rainfall √
(iv) Mismanagement of water resources
(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. √
Ans-
(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. √
(9) Make a sketch showing groundwater and water table. Label it.
Ans- The required sketch is shown below:
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