Which of the following has the minimum solubility in water?

What is the solubility product $(K_{sp})$ of a binary sparingly soluble salt $BA$ if a $100 \text{ mL}$ saturated solution of the salt contains $10^{-4} \text{ moles}$ at room temperature?

The solubility of $AgCN$ increases on adding $KCN$ due to the formation of .......

The molar solubility of $PbI_2$ in $0.2 \ M \ Pb(NO_3)_2$ solution in terms of solubility product of $PbI_2$ is

The solubility product of $AB_2$ is $8 \times 10^{-5} \ M^3$. If the salt is $80 \ \%$ dissociated in a saturated solution,find the solubility of the salt in $M$.

Solid $Ba(NO_3)_2$ is gradually dissolved in $1 \times 10^{-4} \ M \ Na_2CO_3$ solution. At what concentration of $Ba^{+2}$ will the precipitation of $BaCO_3$ start? (Given: $K_{sp}$ of $BaCO_3 = 5.1 \times 10^{-9}$)