Which substance precipitates when $HCl$ is added to a solution of $SnS$ in yellow ammonium sulfide?

Assertion : $BaCO_3$ is more soluble in $HNO_3$ than in plain water.
Reason : Carbonate is a weak base and reacts with the $H^+$ from the strong acid,causing the barium salt to dissociate.

The solubility of a sparingly soluble salt $AX_2$ is $1 \times 10^{-4} \ mol \ dm^{-3}$ at $298 \ K$. Calculate its solubility product $(K_{sp})$?

Precipitation of $CaF_2$ $(K_{sp} = 1.7 \times 10^{-10})$ occurs when equal volumes of which of the following are mixed?

Using the Gibbs energy change,$\Delta G^{o} = +63.3 \ kJ \ mol^{-1}$,for the following reaction in water at $25 \ ^{\circ}C$,calculate the solubility product constant $(K_{sp})$:
$Ag_{2}CO_{3(s)} \rightleftharpoons 2Ag^{+}_{(aq)} + C{O_{3}}^{2-}_{(aq)}$
$(R = 8.314 \ J \ K^{-1} \ mol^{-1})$

Why only $As^{3+}$ gets precipitated as $As_2S_3$ and not $Zn^{2+}$ as $ZnS$ when $H_2S$ is passed through an acidic solution containing $As^{3+}$ and $Zn^{2+}$?