A solid mixture contains four constituents P, Q, 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 from of tiny particles of a material whose corrosion is called resting. 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

(a) P is sand ; Q is common salt ;R is iron filings ; S is ammonium chloride (b) First separate R (iron filings) by using a magnet to attract them. Then separte ammonium chloride by sublimation. Shake sand and common salt with water and filter. Sand obtained as residue. Evaporate filtrate to dryness to obtain common salt