(i) An inorganic compound (A) is formed on passing a gas (B) through a concentrated liquor containing sodium sulphide and sodium sulphite. (ii) On adding (A) into a dilute solution of silver nitrate, a white precipitate appears which quickly changes into a black coloured compound (D). (iii) On adding two or three drops of ferric chloride into the excess of solution of (A), a violet coloured compound (D) is formed. this colour disappears quickly. (iv) On adding a solution of (A) into the solution of cupric chloride, a while precipitate is first fomred which dissolves on adding of (A) forming a compound (E). Identify (A) to (E) and give chemical equations for reactions at step (i) to (iv).

(i) An inorganic compound (A) is formed on passing a gas (B) through a

1.	(i) An inorganic compound (A) is formed on passing a gas (B) through a concentrated liquor containing sodium sulphide and sodium sulphite. (ii) On adding (A) into a dilute solution of silver nitrate, a white precipitate appears which quickly changes into a black coloured compound (D). (iii) On adding two or three drops of ferric chloride into the excess of solution of (A), a violet coloured compound (D) is formed. this colour disappears quickly. (iv) On adding a solution of (A) into the solution of cupric chloride, a while precipitate is first fomred which dissolves on adding of (A) forming a compound (E). Identify (A) to (E) and give chemical equations for reactions at step (i) to (iv).
Answer» Solution :`A=Na_(2)S_(2)O_(3), B=I_(2), C=Ag_(2)S, D=[FE(S_(2)O_(3))_(2)]^(-), E=Na_(4)[Cu_(6) (S_(2)O_(3))_(5)]`