Question

A solution when diluted with water and boiled, it gives a white precipitate. On addition of excess $N{H}_{4}Cl/N{H}_{4}OH$, the volume of precipitate decreases leaving behind a white gelatinous precipitate. Identify the precipitate which dissolves in $N{H}_{4}Cl/N{H}_{4}OH$

• A. $Zn(OH{)}_2$
• B. $Sr(OH{)}_2$
• C. $Mg(OH{)}_2$
• D. $Ca(OH{)}_2$

Answer 1

The correct option is A $Zn(OH{)}_2$

Due to the formation of tetraamminezinc(II) complex:
$Z{n}^{2+}+N{H}_{4}OH\to \left[Zn\right(N{H}_3{)}_4{]}^{2+}$