Assign $A, B, C, D$ from the given type of reaction.
$FeS \downarrow + 2HCl \longrightarrow FeCl_2 + H_2S \uparrow$

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

If the solubility of $Ca_3(PO_4)_2$ in water is $x \ mol \ L^{-1}$, its solubility product in $mol^5 \ L^{-5}$ is (in $x^5$)

The solubility product $(K_{sp})$ for sodium chloride is $36 \text{ mol}^2/\text{L}^2$. The solubility of sodium chloride is:

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 $PbI_2$ at $25 \, ^\circ C$ is $0.7 \, g \, L^{-1}$. What is the solubility product $(K_{sp})$ of $PbI_2$ at this temperature? (Molar mass of $PbI_2 = 461.2 \, g \, mol^{-1}$)