Changes Around Us

Ring of iron blade heated before fixing it into handle of a tool because on heating ring becomes slightly larger in size, therefore it expand and handle fits easily into it.

When we keep on heating water in a pan, the quantity of water in the pan decreases.

a) Drying the wet clothes.
b) Liquid water into water vapour.

The quantity of water in a pan decreases when we keeps on heating it because water changes into its vapour

Melting of ice cream and changing shape of cloth by folding it.

a) Breaking a glass.
b) Preparing curd from milk.

1. False
2. True
3. False
4. True

Conversion of water into water vapour is a reversible change because water vapour when cooled gets converted into liquid water again.

An iron expands and becomes soft on heating. Then it can be changed into desired shape.

If we take some wax in a pan and heat it, this change can be reversed.

Melting of ice is a reversible change because on melting ice changes into water but the water can again be freezed to change it into ice

A change may occur by heating a substance or by mixing it with some other.

Match stick changes into ash and this is a change that cannot be reversed.

We can reverse this change by evaporation of water by which salt can be obtained. Water vapours are condensed to get liquid water.