1.
When we keep on heating in a pan, the quantity of water in the pan decreases.
2.
Match stick changes into ash and this is a change that can not be reversed.
3.
Yes, its a reversible change.
4.
changing, reversible.
5.
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.
6.
Metal rim is made slightly smaller than the wooden wheel. On heating rim expands and fits into wheel. Cold water is then poured over rim, which contracts and tightly onto the wheel.
7.
Iron blade of tools has a ring in which the wooden handle is fixed. Normally the ring is slightly smaller in size than wooden handle. To fix handle ring is heated and it expands. Now handle easily fits into the ring. When ring cools down it contracts and fits into handle.
8.
The shape and size of balloon can be changed by blowing it.
9.
Cold milk is heated for sometime and it becomes hot. Its a reversible change because again it will be cold.
10.
We can reverse this change by evaporation of water by which salt can be obtained. Water vapours are condensed to get liquid water.
11.
Because its a irreversible change which can not be reverse.
12.
Reversible.
13.
Force can bring changes in certain things. For example: when you blow air in a balloon, the force of air inflates the balloon. When a potter applies force on a lump of soil, he gives shape to the lump. When a goldsmith hammers a piece of gold, he makes intricate designs on it. When a ball of dough it pressed with the rolling pin, it turns into flat bread; which is ready to cook.
14.
The causes of changes are: Force and Temperature.
15.
The two examples are: a). Drying the wet clothes; b). Liquid water into water vapour.
16.
heating, mixing
17.
Water vapour
18.
Not be reversed.
19.
When ice is kept on room temperature, it melts and turns into water. When candle begins burning, its wax melts because of higher temperature. When a piece of paper is burnt, it turns into a new substance because of heat. Ironsmith uses heat to change a lump of iron into useful items. Iron is heated till it becomes red hot and then is beaten to give it a particular shape. Spade, knife, sickle, etc. are made from iron in this way.
20.
Irreversible
