22. In chemical terms, what are alums used for purifying water for drinking purposes ? A.Hydrated chlorides B.Double nitrate C.Double sulphates D.Nitrates of aluminium
Answer: Option C Solution: Alum is double sulphates having the composition M2SO4. M2(SO4)3.24H2O. Where M stands for monovalent basic radicals. Alums have Germicide properties and thus used in purification of water.
