$M^{n+}(aq.) + KI \to X\downarrow \text{ (ppt.)}$ $\xrightarrow{Excess KI} \text{ppt. remains insoluble in excess } KI \text{ solution. Then cation } M^{n+}(aq.) \text{ can be}$

Passing $H_2S$ gas into a mixture of $Mn^{2+}$,$Ni^{2+}$,$Cu^{2+}$ and $Hg^{2+}$ ions in an acidified aqueous solution precipitates

$A$ solution contains $Cl^{-}$,$I^{-}$,and $SO_{4}^{2-}$ ions. Which of the following ions is capable of precipitating all of the above when added to this solution?

Which of the following pair of cations can be separated by excess $NaOH$ solution?

Addition of sodium thiosulphate solution to a solution of silver nitrate gives $X$ as a white precipitate, which is insoluble in water but soluble in excess thiosulphate solution to give $Y$. On boiling in water, $Y$ gives $Z$. $X$, $Y$, and $Z$ respectively are:

Which of the following gives a black precipitate when $H_2S$ gas is passed through its solution?