$A$ black sulphide is formed by the action of $H_2S$ on

$Fe^{2+}$ ion can be distinguished from $Fe^{3+}$ ion by

When $MgSO_4$ is treated with $NH_4OH$ and $Na_2HPO_4$,a white crystalline solid is formed. What is its formula?

Aqueous solution of $FeSO_4$ does not produce a precipitate with:

When a salt is treated with sodium hydroxide solution,it gives gas $X$. On passing gas $X$ through reagent $Y$,a brown-coloured precipitate is formed. $X$ and $Y$ respectively,are

Which reagent can be used to identify nickel ion $(Ni^{2+})$?