A. Fill in the blanks
1. About ___________ of water is present in oceans and seas.
2. Only 0.3 per cent of fresh water available for use is present in rivers, ___________ and ___________.
3. Ground water is drawn from wells, ___________ and ___________.
4. Use of ___________ and ___________ for irrigation reduces wastage of water.
5. The network of pipes which carries waste water to water treatment plant is called ___________.
Answer:
(1) 97%
(2) lakes, streams
(3) tubewells, hand pumps
(4) sprinkler, drip technique
(5) sewerage system
B. Write True or False for the following statements:-
1. About 97 per cent of water on earth is fresh water and is good for human use.
2. Water occurs in its solid form in glaciers and ice caps.
3. Farmers rely on ground water for irrigating their crops when there is no rain.
4. Deforestation increases the level of groundwater.
5. More use of ground water causes decrease in water table.
Answer:
(1) False
(2) True
(3) True
(4) False
(5) True
C. Tick the correct option.
1. Ocean water is unfit for drinking as it is-
2. ‘Rain water harvesting’ can help us to conserve-
Answer:
3. On the earth, the percentage of water, that is fresh and readily available for use, is, nearly-
Answer: 0.3%
4. One of the important factors, that can lead to a scarcity of water, is-
Answer:
5. “Waste water is also called-
Ans 1. very salty
Ans 2. Rainwater
Ans 3. 0.3 %
Ans 4. deforestation
Ans 5. sewage
D. Answer the following questions in brief:
1. Name the three forms in which water exists on the earth.
Answer: Water on the earth is present in three forms: ice ( solid in nature), water ( liquid form), water vapours ( gaseous form)
2. Give the meaning of the term ‘water table’.
Answer: Groundwater has different layers. Its upper layer is termed the water table.
3. Name two methods of drawing out ground water.
Answer: The Two methods of drawing out groundwater are as follows:-
- Using the water wheel
- With the help of tubewells
4. Name two activities that lead to the formation of sewage.
Answer: Washing clothes near lakes and ponds, Bathing of people and animals near the rivers and other water bodies.
5. State any two precautions that can help avoid the ‘choking of drains.
Answer: two precautions that can avoid choking of drains are –
1. Do not throw waste material like peels, wrappers etc in the drains
2. Using a wastage stopper on the top of the drains.
E. Answer the following questions
1. How is increase in population responsible for shortage of water?
Answer: Increase in population means more people in each area. More peoplewill be dependent on the same water bodies. This will create a situation of water scarcity.
2. Discuss, in brief, how ‘Rain water harvesting’ can be done.
Answer: There are different methods of rainwater harvesting. Houses and structures can be built in such a way that the water gets collected in one place. We can also make use of underground water tanks to store the water.
3. Discuss any two causes that lead to a decrease in ground water level.
Answer: The two causes that can lead to a decrease in groundwater level are:
Increased number of borewells being dug by people in the urban areas. This leads to a decrease in the groundwater level.
Less rainfall may also cause a decrease in the groundwater level because we then become dependent more on the groundwater.
4. How can ‘better management of water resources’ help in the conservation of water?
Answer: Better management of resources can help in conserving the water. We should not allow animals to bathe in the river bodies. Any leakage in the water pipelines should be repaired as soon as possible.
The river bodies can be directed towards the farms to save water. We can make use of sprinklers and drip irrigation methods to preserve the water.
5. Write, in brief, about the basic details and the role of the ‘sewerage system’.
Answer: A sewage system carries the waste water. It is very crucial to have it in order to keep the surroundings clean. It is done by using pipes that are connected to each other.
The sewage system carries the waste through the drains. The water is then directed towards the waste water treatment plant where it is cleaned and after that gets mixed the freshwater river bodies. This process a large network of pipes.
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