2nd Class Science Air, Water and Weather Water


Category : 2nd Class

*      Water


Water is the second most necessary requirement for the living organism. Living organism cannot survive without air for more than few minute. They also cannot survive without water for more than 3 days. Most part of our body is made up of water. Hence our body require water regularly because of excretion of waste water from the body.


*          Potable Water


Potable water is drinking water. This water is not polluted or contaminated and quality of this kind of water is high. Therefore, it can be used for drinking. If human and other living organisms do not get potable water they can suffer from waterborne diseases. Commonly water supplied in household is potable. People also use water purifier to make water potable. Persons who do not have access to potable water are prone to water borne diseases.


*          Sources of Water


Water is not man-made. It is a natural resource like air, sun, etc.


The following are the natural source of water:



           Well                            Rain                         Ground water                    River  



        Pond                            Ocean                           Lake                            Glacier  


*          Water on the Earth


Water is found in many places on the earth's surface, below the surface, and in the atmosphere. Water travels between different areas of the earth, known as the water cycle. Out of hundred, about 70 part of the earth surface is covered with water, and most of that is in the ocean. Only a small portion of the water of the earth is freshwater, which is found in rivers, lakes and groundwater. Freshwater is needed for drinking, farming, and washing. In addition to liquid water, water is also present on the earth in the form of ice. Without water, life is not possible.


*           States of Water


There are three states of water on the surface of the earth which are given below:

Solid state of water is called ice.

Liquid state is water itself.

Gaseous state of water is called water vapour.


*          Water Cycle


Forms of water on the earth is always changing and this change makes water cycle. Water can be in the form of solid, liquid and gas. Ice is a solid state of water and can change into water or water vapour. Water can change into solid (ice) or gas (water vapour). Water vapor can also change into ice or water. In fact, water cycle works on the addition or subtraction of heat. If heat is given to ice, it melts. If heat is given to water, it evaporates. Evaporation converts liquid water into a gas called water vapor.

If heat is taken away from water vapor, it condenses. Condensation converts water vapor (gas) into liquid form of water. If heat is taken away from liquid water, it freezes and convert into ice.

The another name of water cycle is hydrologic cycle. In this cycle, water from oceans, lakes, rivers and plants is converted into water vapor. Water vapor condenses into millions of tiny droplets to form clouds. Clouds lose their water as rain or snow, which is called precipitation. Precipitation is either absorbed into the ground or runs off into water bodies like rivers, ponds, lakes, oceans etc. Water that was absorbed into the ground is taken up by plants. Plants lose water from their surfaces as vapor back into the atmosphere. Water that runs into rivers, ponds, lakes, or oceans evaporates due to the heat of the Sun to go back into the atmosphere.


Look at the following picture of water cycle:






      Potable water is _____________ water

(a) Sea

(b) River

(c) Ground

(d) Drinking


Answer: (d)


Drinking water is potable water. Therefore, option (D) is correct and rest of the options is incorrect.



       Which one of the following is obtained after melting the ice?

(a) Oxygen

(b) Water

(c) Carbon dioxide

(d) None of these


Answer: (b)


Ice is melted into water. Therefore, option (B) is correct and rest of the options is incorrect. 

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