3rd Class Science Weather, Air and Water Water and its Different States

     Water and its Different States

Water is a wonderful liquid that dissolves many substances in it. Life is impossible without water.

          Different States of Water

Water, ice, and water vapours are three states of water. All the three forms are interconvertible.

Look at the following picture of the changes of water, from one state to another:

           Inter conversion of different states of water

One state of water can be converted into another either by gaining energy or by releasing.

Freezing is changing the state of water into ice. It occurs at 0°c.

When water gets heated, it is converted into water vapor. This process is called vaporization. The boiling point of water is 100°c.  

       Evaporation

Water is also changes its state in the form of water vapor from the rivers, ponds, lakes, oceans, due to Sun's heat and results in the formation of clouds. This process is called evaporation.

Evaporation becomes faster in the following conditions:

(A) In sunny days

(B) In windy day

(C) When temperature is more

(D) In less humid air

(E) When surface area is larger

Water evaporates fast in sunshine.

Clothes dry up quickly in windy day.

Rate of evaporation becomes faster at high temperature.

Warmer day temperature is of 40°C.

.

After 4 - 5 hours (Potato chips dry up)

Colder day temperature is of 25°C .

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After 4 - 5 hours (Potato chips still wet)

Dry air absorbs water vapour fast as compared to humid air. Presence of water vapour make it humid. Humid air has lots of water vapor.

                  Dry up fastly                                                     Dry up slowly

Large surface area allows more water vapour to escape

       Space occupied by all three states of water

Ice (solid state) has definite shape and size. Whereas water, if kept in glass, takes the shape of glass and if same water is poured in the bowl, it takes the shape of the bowl. Water, therefore, has no definite shape. It takes the shape of the containers, in which it is poured.

Water vapor, gaseous state of water is formed on heating, and occupies the whole space available for it.

         Water Cycle

Sun's heat evaporates water of river, lakes, ponds, seas in to water vapor. Being lighter than water, it rises up high in the sky. On coming in contact with cool air, it changes into tiny drops of water called condensation and when many drops of water joined together clouds are formed.

Clouds, when loaded with drops of water become heavy and fall down in the form of rain, which is known as precipitation. Rain fall over land, river, lakes, ponds, seas and everywhere. Again the water from these sources evaporate, form clouds and rains back. This process is repeated again and again, which is called water cycle.

Look at the following picture of water cycle:

Snow appears to us as small balls of cotton. Generally snow falls at higher altitudes i.e. on mountains and hilly areas. People go to the hill stations to view beautiful scene of snow falling. Sometimes, the drops of water floating in the air are cooled down to a very low temperature, it then turns to snow and falls on the ground. Sometimes strong winds take these water droplets to a colder regions, where it freezes into small ice balls and falls to the ground which is called hail. During winter season, often in the morning we see small drops of water on the surfaces of grasses and leaves. These small drops of water are called dew drops. It appears like a shining transparent ball of water. When these dew drops freezes frosts are formed, which damages the plants.   

    Which one of the following makes the ground water harmful?

(a) Insecticides

(b) Pesticides

(c) Fertilizers

(d) All of these

(e) None of these

Answer: (d)

Explanation

Ground water becomes dirty and toxic when insecticides, pesticides, fertilizers etc. reaches into it. Therefore, option (d) is correct and rest of the options is incorrect.

      Which one of the following statements is not true?

(a) Water is present in the snow form, in mountains.

(b) When we heat ice, it becomes water.

(c) Condensation process involves in the formation of water vapour.

(d) Water freezes at 0°c

(e) None of these

Answer: (c)

Explanation

Formation of water vapour occurs due to evaporation. Therefore, option (c) is correct and rest of the options is incorrect.