Question

Give reasons for the following : 

(a) Solids have a definite shape and are highly rigid while gases have to definite shape and are least rigid. 

(b) Sugar can be distinguished from talcum powder using water. 

(c) Water on freezing turns into ice. 

(d) A bottle of perfume on opening evolves an odour which can be sensed over a long distance.

Answer 1

(a) Solids have very closely packed atoms with minimum spaces between them while gases have atoms which are for apart with maximum spaces between them. Solids have a definite shape and are highly rigid while gases have no definite shape and are least rigid. 

(b) Sugar is soluble in water whereas talcum powder is not. 

(c) Every pure substance has a fired melting point or boiling point. 

(d) A bottle of perfume on opening evolves an odour because gases diffuse very easily and odour spreads over a large distance.