Which of the following substances is insoluble in acetic acid $(CH_3COOH)$?

The $K_{sp}$ of $CaF_2$ is $1.7 \times 10^{-10}$. What is the volume in $mL$ of a saturated solution containing $10 \ mg$ of $CaF_2$? (Molecular mass of $Ca = 40, F = 19$).

Consider two Group $IV$ metal ions $X^{2+}$ and $Y^{2+}$. $A$ solution containing $0.01 \ M$ $X^{2+}$ and $0.01 \ M$ $Y^{2+}$ is saturated with $H_2S$. The pH at which the metal sulphide $YS$ will form as a precipitate is . . . . . . (Nearest integer). (Given: $K_{sp}(XS)=1 \times 10^{-22}$ at $25^{\circ} C$, $K_{sp}(YS)=4 \times 10^{-16}$ at $25^{\circ} C$, $[H_2S]=0.1 \ M$ in solution, $K_{a1} \times K_{a2}(H_2S)=1.0 \times 10^{-21}$, $\log 2=0.30, \log 3=0.48, \log 5=0.70$)

The solubility of $CaCl_2$ is $1.11 \times 10^{-8} \ g/100 \ mL$. If the molar mass of $CaCl_2$ is $111 \ g/mol$,find the $K_{sp}$.

Which compound is soluble in $NH_4OH$?

Solubility product $(K_{sp})$ of salts of type $MX$,$MX_2$,and $M_3X$ at temperature $T$ are $4 \times 10^{-8}$,$3.2 \times 10^{-14}$,and $2.7 \times 10^{-15}$ respectively. The solubility of the salts at temperature $T$ are in the order: