(a) Crystals of a substance their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down. Name the substance and write its formula and explain the phenomenon involved. (b) name the acid and base that would be used to prepare the following salts: (i) Potassium sulphate (ii) Ammonium chloride.

(a) Crystals of a substance their colour on heating in a closed test t

1.	(a) Crystals of a substance their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down. Name the substance and write its formula and explain the phenomenon involved. (b) name the acid and base that would be used to prepare the following salts: (i) Potassium sulphate (ii) Ammonium chloride.
Answer» Solution :(a) COPPER sulphate crystals `(CuSO_4. 5 H_2O)` 5 molecules of water are present in ONE formula unit of copper sulphate. When heated, it loses its water and salt turns white. (b) BASIC Salt: (i) Base: KOH (Potassium HYDROXIDE) Acid: `H_2SO_4` (Sulphuric acid) (ii) Base: `NH_4OH` (Ammonium hydroxide) Acid: HCl (HYdrochloric acid)