JEE Main 2025 — Ionic Equilibrium Question with Solution

Condition for precipitation ${\mathrm{Q}}_{\text{ip }}>{\mathrm{K}}_{\text{sp }}$ For $\left[\mathrm{A}(\mathrm{OH}{)}_2\right]$ $\begin{aligned} & {\left[\mathrm{A}^{2+}\right][\mathrm{OH}]^2>9 \times 10^{-10}} \\ & {\left[\mathrm{~A}^{+2}\right]=1 \mathrm{M}} \\ & \Rightarrow\left[\mathrm{OH}^{-}\right]>3 \times 10^{-5} \mathrm{M} \end{aligned}$ For $\left[\mathrm{B}(\mathrm{OH}{)}_3\right]$ $\begin{aligned} & {\left[\mathrm{B}^{3+}\right]\left[\mathrm{OH}^{-}\right]^3>27 \times 10^{-18}} \\ & {\left[\mathrm{~B}^{3+}\right]=1 \mathrm{M}} \\ & \Rightarrow\left[\mathrm{OH}^{-}\right]>3 \times 10^{-6} \mathrm{M} \end{aligned}$ So, $\mathrm{B}(\mathrm{OH}{)}_3$ will precipitate before $\mathrm{A}(\mathrm{OH}{)}_2$