Ionic Equilibrum - Physical Chemistry - Chemistry Previous Year Questions

At $T(\mathrm{~K})$ in a saturated solution of $\mathrm{MgCO}_3$ and $\mathrm{Ag}_2 \mathrm{CO}_3$, if the concentration of $\mathrm{Mg}^{2+}$ ion is $3.2 \times 10^{-5} \mathrm{M}$, then the concentration of $\mathrm{Ag}^{+}$ion in the solution will be [Given, $K_{\mathrm{sp}}\left(\mathrm{MgCO}_3\right)=1.6 \times 10^{-6}$ and $K_{\mathrm{sp}}\left(\mathrm{Ag}_2 \mathrm{CO}_3\right)=8.0 \times 10^{-12}$ at $T(\mathrm{~K})$ ]

200 mL of an aqueous solution of $\mathrm{HCl}(\mathrm{pH}=2)$ is mixed with 300 mL of aqueous solution of NaOH $(\mathrm{pH}=12)$ and is diluted to 1.0 L . The pH of the resulting solution is ( $\mathrm{pH}=2$ )

The volume of water required to dissolve $0.1 \mathrm{~g} \mathrm{PbCl}_2$ to get a saturated solution (in mL ) is (Given $K_{s p}\left(\mathrm{PbCl}_2\right)=3.2 \times 10^{-8}$; Atomic mass of $\mathrm{Pb}=207 \mathrm{u}$ )