Which of the following are chemical changes?

(i) decaying of wood

(ii) burning of wood

(iii) sawing of wood

(iv) hammering of nail into wood

Tincture of iodine has antiseptic properties. This solution is made by dissolving:

Which of the following are physical changes?

(i) melting of iron metal

(ii) rusting of iron metal

(iii) bending of an iron rod

(iv) drawing wire of iron metal

Many indigestion mixtures are suspensions. What do the instructions written on the bottle of an indigestion mixture tell us before taking the mixture, and why?

Three mixtures A, B and C are obtained by stirring three different solids in water taken in separate beakers. When mixture A is allowed to stand for some time, then its particles settle at the bottom of the beaker. When a beam of light is passed through mixture A in a dark room, the path of light becomes visible when observed from the side of the beaker. When mixture B is allowed to stand for a considerable time, even then its particles do not settle down. Mixture B, however, scatters the beam of light just like mixture A. The particles of mixture C do not settle down on keeping and it also does not scatter a beam of light passing through it.

(a) What are the mixtures like A known as?

(b) What are the mixtures like B known as?

(c) What are the mixtures like C known as?

(d) Name the phenomenon exhibited by A and B which occurs on passing a beam of light through them.

(e) Name one mixture each which is like (i) A (ii) B, and (iii) C.