Which of the following is least soluble in water?

What is the expression for the solubility product of silver chromate $(Ag_2CrO_4)$ if its solubility is expressed as $S \ mol \ L^{-1}$?

Solubility product $(K_{sp})$ of salts of type $MX$,$MX_2$,and $M_3X$ at temperature $T$ are $4 \times 10^{-8}$,$3.2 \times 10^{-14}$,and $2.7 \times 10^{-15}$ respectively. The solubility of the salts at temperature $T$ are in the order:

The $K_{sp}$ values of $Ag_2CrO_4, AgCl, AgBr,$ and $AgI$ are $1.1 \times 10^{-12}, 1.8 \times 10^{-10}, 5.0 \times 10^{-13},$ and $8.3 \times 10^{-17}$ respectively. If $AgNO_3$ solution is added to a solution containing equal moles of $NaCl, NaBr, NaI,$ and $Na_2CrO_4$,which will precipitate last?

What is the molar solubility of $Al(OH)_3$ in $0.2 \ M \ NaOH$ solution? Given that,the solubility product of $Al(OH)_3 = 2.4 \times 10^{-24}$.

What is the solubility of $BaSO_4$ in $\text{g/dm}^3$ if its solubility product is $1.0 \times 10^{-10}$ at $25^\circ\text{C}$? [Molar mass of $BaSO_4 = 233 \text{ g/mol}$]