The solubility product of a sparingly soluble salt is defined as the product of the ionic concentrations in a:

The solubility product of magnesium hydroxide $Mg(OH)_2$ is $1.2 \times 10^{-11}$. Calculate its solubility in pure water and $0.05 \ M$ $NaOH$.

The solubility of $PbI_2$ at $25\,^{\circ}C$ is $0.7\, g\, L^{-1}$. The solubility product of $PbI_2$ at this temperature is (molar mass of $PbI_2 = 461.2\, g\, mol^{-1}$)

The solubility products of $NiS$,$ZnS$,$CdS$,and $HgS$ are $4.7 \times 10^{-5}$,$1.6 \times 10^{-24}$,$8 \times 10^{-27}$,and $4 \times 10^{-53}$ respectively. An aqueous solution contains $Ni^{2+}$,$Zn^{2+}$,$Cd^{2+}$,and $Hg^{2+}$ of equal concentration. $H_2S$ gas was passed into this solution very slowly. The first and the last ions that precipitate as sulphides are respectively.

The moles of $Ag^{+}$ which must be added to decrease the concentration of $Cl^{-}$ from $4 \times 10^{-5} \ M$ to $10^{-5} \ M$ in $100 \ mL$ solution,if $K_{sp}$ for $AgCl$ is $10^{-10} \ M^2$ at $25 \ ^oC$.

Which one of the following is most soluble?