$A$ colourless crystalline salt $X$ is soluble in dilute $HCl$. On adding $NaOH$ solution,it gives a white precipitate which is insoluble in excess of $NaOH$. $X$ is

Sodium nitroprusside when reacts with a solution of $Na_2S$,produces:

An inorganic compound $X$ on treatment with concentrated $H_{2}SO_{4}$ produces brown fumes and gives a dark brown ring with $FeSO_{4}$ in the presence of concentrated $H_{2}SO_{4}$. Also,compound $X$ gives a 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 a deep blue coloured solution. Compound $X$ is:

What color does lead acetate give with $H_2S$?

An aqueous solution containing $FeSO_4$,$Al_2(SO_4)_3$,and chrome alum is treated with $Na_2O_2$ and heated,followed by filtration. The resulting products are:

Which sulfide is soluble in $(NH_4)_2CO_3$?