If the solubility of $Ca_3(PO_4)_2$ in water is $x \ mol \ L^{-1}$, its solubility product in $mol^5 \ L^{-5}$ is (in $x^5$)

Solubility of calcium phosphate (molecular mass,$M$) in water is $W \ g$ per $100 \ mL$ at $25^{\circ} C$. Its solubility product at $25^{\circ} C$ will be approximately.

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 $PbS$?

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

Which of the following has the maximum solubility? ($K_{sp}$ values are given in parentheses.)