Question

Consider $\left(1\right)$ $Zn(OH{)}_2$ $\left(2\right)$ $Cr(OH{)}_3$ $\left(3\right)$ $Mg(OH{)}_2$ $\left(4\right)$ $Al(OH{)}_3$ which hydroxide is precipitated by $N{H}_{4}OH$ containing $N{H}_{4}Cl$?

• A. $1,2$
• B. $2,4$
• C. Only $4$
• D. $1,2,3$ and $4$

Answer 1

The correct option is B $2,4$

$Zn(OH{)}_2$ and $Mg(OH{)}_2$ are soluble in $N{H}_{4}OH$.

$Cr(OH{)}_3$ and $Al(OH{)}_3$ are not soluble in $N{H}_{4}OH$ due to less solubility. Hence forms precipitate.