CLASS - 3 || SUBJECT - SCIENCE || LESSON – 9 || WATER AS A RESOURCE ||

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LESSON – 9


WATER AS A RESOURCE

 

1.    State of water is interchangeable. How?

Water exist in e states, ice, water, and water vapour. All the three states are interchangeable. Ice can be changed into water by melting. Water can be changed into water vapour by evaporation. Water vapour can be brought back to water by condensation. water can also be changed in to ice by freezing.

 

2.    What is water cycle? Explain it with labelled diagram.

The cycle that involves the change of water into water vapour and then into water again in nature is called the water cycle. It is the process by which water circulates between the sky and the earth in a continuous cycle.

 

 

 

ICE

Heating

 

 

Water

heating

 

 

Water vapour

 

 

Cooling

Cooling

 

 

3.    What do you mean by purification of water?

Impure water is not fit for drinking. It is essential to purify the water before consuming it. The process of removal of germs and impurities from water to make it fit for drinking is called water purification.

 

4.    Write in brief any two methods of purification of water.

The methods that we use generally to make water portable are:

Boiling:-  boiling is the simplest method of purification. Boiling also kills harmful germs present in water

 

Using water purifiers:- water purifier not only removes impurities but it also removes harmful germs from water. These purifiers use different type of micro filters to remove impurities.

 

5.    Write two soluble and two insoluble impurities present in water.

The impurities present in water are of two types:

a.    Soluble impurities -  salts and minerals

b.    Insoluble impurities – stone, sand

 

6.    Why is rainwater harvesting important?

Rainwater harvesting is important because water is a precious resource. We should save it and use it judiciously. Rainwater is an important source of water. There is a technique for saving rainwater. This is called rainwater harvesting. We can use it for many purposes.

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