$A$ precipitate of calcium oxalate will not dissolve in

The solubility product of a sparingly soluble salt $AX_2$ is $3.2 \times 10^{-11}$. Its solubility (in moles/litres) is

If the solubility product of lead iodide $(PbI_2)$ is $3.2 \times 10^{-8}$,then its solubility in $moles/litre$ will be

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

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Pb(AcO)_2 + H_2S \longrightarrow PbS \downarrow + 2AcOH$

Silver ions are added to a solution with $[Br^{-}] = [Cl^{-}] = [CO_3^{2-}] = [AsO_4^{3-}] = 0.1 \ M$. Which compound will precipitate with the lowest $[Ag^{+}]$ concentration?