An inorganic Compound ' X ' on treatment with concentrated H 2 SO 4 produces brown fumes and gives dark brown ring with FeSO 4 in presence of concentrated H 2 SO 4 . Also Compound ' X ' gives precipitate ' Y ' , when its solution in dilute HCl is treated with H 2 S gas. The precipitate ' Y ' on treatment with concentrated HNO 3 followed by excess of NH 4 OH further gives deep blue colo