Which compound is soluble in $NH_4OH$?

When equal volumes of the following solutions are mixed,precipitation of $AgCl$ $(K_{sp} = 1.8 \times 10^{-10})$ will occur only with:

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?

The solubility product of $PbI_{2}$ is $8.0 \times 10^{-9}$. The solubility of lead iodide in $0.1 \ M$ solution of lead nitrate is $x \times 10^{-6} \ mol/L$. The value of $x$ is ....... .(Rounded off to the nearest integer)
$[$Given: $\sqrt{2}=1.41]$

Which of the following equations represents the solubility product $(K_{sp})$ of $As_2S_3$?

Which of the following is most soluble in water?