QJEEM25Ch086a: JEE Main 2025 Chemistry - Class 11 JEEM25Ch086a Solution: Which of the following happens when is added gradually to the…

Condition for precipitation \mathrm{Q}_{\mathrm{ip}}>\mathrm{K}_{\text {sp }}

For $\left[\mathrm{A}(\mathrm{OH})_2\right.$ ]

\begin{aligned}& {\left[\mathrm{A}^{2+}\right]\left[\mathrm{OH}^{-}\right]^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 $\mathrm{A}(\mathrm{OH})_2$