Question

A solid mixture contains four constituents P, Q, R and S.P consists of tiny grains and it is mixed with cement for plastering the walls. Q is a white solid which is recovered on a large scale from sea water by the process of evaporation. R is in the form of tiny particles of a material whose corrosion is called rusting. And S is a white-solid which is used in making ordinary dry cells.

(a) What could P, Q, R and S be ?

(b) How would you separate a mixture containing P, Q, R and S ?

Answer 1

(a) P is sand; Q is common salt; R is iron fillings; S is ammonium chloride.

(b) We first separate R (iron filings) by using a magnet to attract them. Then, separate S (ammonium chloride) by sublimation. Now, we shake P(sand)and Q(common salt) with water and filter. P(sand) is obtained as residue. Now, we evaporate filtrate to dryness to obtain Q(common salt).