For the precipitation of $AgCl$ by $Ag^{+}$ ions and $HCl$,which of the following is true?

Which of the following happens when $NH_{4}OH$ is added gradually to the solution containing $1 \ M \ A^{2+}$ and $1 \ M \ B^{3+}$ ions?
Given: $K_{sp}[A(OH)_{2}] = 9 \times 10^{-10}$ and $K_{sp}[B(OH)_{3}] = 27 \times 10^{-18}$ at $298 \ K$.

Assign $A, B, C, D$ from the given type of reaction.
$HgS(s) + Na_2S(aq) \rightleftharpoons Na_2[HgS_2](aq)$

On passing $H_2S$ gas through a solution of $Cu^{2+}$ and $Zn^{2+}$ ions,$CuS$ is precipitated first because

Assign $A, B, C, D$ from the given type of reaction.
$ZnS(s) + 2HCl(aq) \longrightarrow ZnCl_2(aq) + H_2S(g)$

At $25^{\circ} C$,the solubility product of $MCl$ is $1 \times 10^{-10}$. What is its molar solubility in $0.1 \ M \ NaCl$ solution at the same temperature?