A compound (A) is greenish crystalline salt, which gave the following reactions. (i) Additon of BaCl2 solution to the solution of (A) results in the formation of white precipitate (B) which is insoluble in dilute HCl. (ii) On heating (A), water vapours and two oxides of sulphur (C) and (D) are liberated leaving a red brown residue(E). (iii) (E) dissolves in warm conc. HCl to give a yellow solution (F) (iv) Solution (F) on treatment with thiocyanate ions gives blood red colouerd compound (G). Identify the substances from (A) to (G).