Give reasons for the following statements.

(a) Solids are rigid and incompressible.

(b) Change in temperature cause changes in state of matter.

(c) Liquids take the shape of the container.

(d) Ice changes to water and water changes to steam.

(e) Water droplets form on a glass of cold water.

(a) In solids, molecules are closely packed and the intermolecular space between them is very less. The molecules remain fixed and vibrate about their mean positions. Hence, solids keep their shape rigid (fixed) and cannot be compressed into a smaller volume (incompressible).

(b) When a substance is heated, its molecules move faster and can break free from their fixed positions, changing from solid to liquid or from liquid to gas. When it is cooled, the molecules slow down and come closer, changing from gas to liquid or from liquid to solid.

(c) In liquids, the intermolecular forces are weaker than in solids. Hence, the molecules are not tightly packed and can slide past one another. This free movement of molecules allows liquids to flow and take the shape of the container in which they are kept

(d) When ice is heated, the molecules present in it start vibrating more and more until they start sliding over each other. Thus, ice changes to water. On heating the water further, the molecules start moving even faster until they become free to move in all directions. Thus, water changes to steam.

(e) The cold glass cools the air around it and the water vapour present in the air loses heat, changes into liquid water, and forms tiny droplets on the outer surface of the glass. This process is called condensation.