Which of the following precipitates does not dissolve even in a large excess of $NH_4OH$?

Which of the following is most soluble in water?

The $K_{sp}$ value of $AgCl$ at $25^{\circ}C$ is $1.8 \times 10^{-10}$. If $10^{-5} \ mol$ of $Ag^{+}$ is added to the solution,the new $K_{sp}$ value will be:

Calculate the molar solubility of $Ni(OH)_2$ in $0.10 \ M \ NaOH$. The solubility product of $Ni(OH)_2$ is $2 \times 10^{-15}$.

If the $[F^{-}] = 2.0 \times 10^{-5} \ M$ in water,how many grams of $CaCl_{2}$ must be added to initiate the precipitation of $CaF_{2}$? Given: $K_{sp}$ for $CaF_{2} = 1.7 \times 10^{-10}$ and the molar mass of $CaCl_{2} = 111 \ g \ mol^{-1}$. Assume the volume of the solution is $1 \ L$.

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 $BaCO_3 = 5.1 \times 10^{-9}$)