Practical Organic Chemistry

An inorganic Compound 'X' on treatment with concentrated H2SO4 produces brown fumes and gives dark brown ring with FeSO4 in presence of concentrated H2SO4. Also Compound ' X′ gives precipitate 'Y', when its solution in dilute HCl is treated with H2S gas. The precipitate ' Y′ on treatment with concentrated HNO3 followed by excess of NH4OH further gives deep blue coloured solution, Compound ' X′ is: