(i) A compound (A) is obtained by boiling aqueous sodium sulphite with sulphur. (ii) Compound (A) is used to titrate iodine in volumetric analysis. (iii) It dissolves AgBr to give (B) and NaBr on addition of excess of (A) to the mixture a complex salt (C) is obtained. (iv) (A) is used in photography for fixing films and prints. Photographic emulsions are made of AgNO_(3). AgCl and AgBr. (v) When a solution (A) is added to CuSO_(4) in cold, the blue solution becomes step-wise brownish green, yellowish green and finally yellow. (vi) If (A) is added to acidic, CuSO_(4), Cu_(2)S is precipitated and if the solution is boiled, CuS is precipitated. What are (A), (B) and (C) ?

(i) A compound (A) is obtained by boiling aqueous sodium sulphite with

1.	(i) A compound (A) is obtained by boiling aqueous sodium sulphite with sulphur. (ii) Compound (A) is used to titrate iodine in volumetric analysis. (iii) It dissolves AgBr to give (B) and NaBr on addition of excess of (A) to the mixture a complex salt (C) is obtained. (iv) (A) is used in photography for fixing films and prints. Photographic emulsions are made of AgNO_(3). AgCl and AgBr. (v) When a solution (A) is added to CuSO_(4) in cold, the blue solution becomes step-wise brownish green, yellowish green and finally yellow. (vi) If (A) is added to acidic, CuSO_(4), Cu_(2)S is precipitated and if the solution is boiled, CuS is precipitated. What are (A), (B) and (C) ?
Answer» SOLUTION :A `=Na_(2)S_(2)O_(3)` `B=Ag_(2)S_(2)O_(3)` C `=NAS[Ag_(3)(S_(2)O_(3))_(4)]`