What is the molar solubility of $Fe(OH)_2$ $(K_{sp} = 8.0 \times 10^{-16})$ at $pH$ $13.0$ ?

Solid $Ba(NO_3)_2$ is gradually added to a $1.0 \times 10^{-4} \, M \, Na_2CO_3$ solution. At what concentration of $Ba^{2+}$ will precipitation start? (Given $K_{sp}$ for $BaCO_3 = 5.1 \times 10^{-9}$)

Solid $Ba(NO_3)_2$ is gradually dissolved in a $1.0 \times 10^{-4} \ M$ $Na_2CO_3$ solution. At what concentration of $Ba^{2+}$ will a precipitate begin to form? ($K_{sp}$ for $BaCO_3 = 5.1 \times 10^{-9}$)

The solubility product of a salt with the general formula $MX_2$ is $4.0 \times 10^{-12}$. What is the concentration of the $M^{2+}$ ion in a saturated solution of this salt?

An excess of $Ag_{2}CrO_{4(s)}$ is added to a $5 \times 10^{-3} \ M$ $K_{2}CrO_{4}$ solution. The concentration of $Ag^{+}$ in the solution is closest to
[ Solubility product for $Ag_{2}CrO_{4} = 1.1 \times 10^{-12}$ ]

What is the concentration of $Ba^{2+}$ when $BaF_2$ $(K_{sp} = 1.0 \times 10^{-6})$ begins to precipitate from a solution that is $0.30 \, M \ F^{-}$?