Which compound is soluble in $NH_4OH$?

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?

The $pH$ of a saturated solution of $Ca(OH)_{2}$ is $9$. The solubility product $(K_{sp})$ of $Ca(OH)_{2}$ is:

The compound not soluble in acetic acid is

The solubility product of $Mg(OH)_2$ is $1.8 \times 10^{-11}$ at $298 \ K$. What is its solubility in $mol \ dm^{-3}$?

The salt having the least solubility in water is