Zinc carbonate is precipitated from zinc sulphate solution by the addition of

The solubility product of $PbS$ is $3.4 \times 10^{-28}$. If $[Pb^{2+}] = 1 \times 10^{-2} \ mol/L$,what concentration of $[S^{2-}]$ is required to precipitate $PbS$?

At $25\,^{\circ}C$,the solubility product of $Mg(OH)_2$ is $1.0 \times 10^{-11}$. At which $pH$ will $Mg^{2+}$ ions start precipitating in the form of $Mg(OH)_2$ from a solution of $0.001\, M\, Mg^{2+}$ ions?

If the solubility product of a base $M(OH)_3$ is $2.7 \times 10^{-11}$,find the concentration of $OH^-$.

Assign $A, B, C, D$ from the given type of reaction.
$CaC_2O_4 \downarrow + CH_3COOH \longrightarrow$ No reaction

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