A light bluish-green crystalline compound responds to the following tests:
(i). Its aqueous solution gives a brown precipitate on reaction with alkaline K2[HgI4] solution.
(ii). Its aqueous solution gives a blue colour with K3[Fe(CN)6] solution.
(iii). Its solution in hydrochloric acid gives a white precipitate with BaCl2 solution. Identify the ions present and suggest the formula of the compound.