Question

Which two sets of reactants best represent the amphoteric character of $Zn{\left(OH\right)}_2$?
Set 1: $Zn{\left(OH\right)}_2\left(s\right)$ and ${OH}^{-}\left(aq\right)$
Set 2: $Zn{\left(OH\right)}_2\left(s\right)$ and $H_{2}O\left(l\right)$
Set 3: $Zn{\left(OH\right)}_2\left(s\right)$ and $H^{+}\left(aq\right)$
Set 4: $Zn{\left(OH\right)}_2\left(s\right)$ and ${NH}_3\left(aq\right)$

• A. 1 and 2
• B. 1 and 3
• C. 2 and 4
• D. 3 and 4

Answer 1

Answer: (B)

1 and 3

Zinc hydroxide is amphoteric in nature.
It reacts with acid as well as base.
$Zn\left(OH{)}_2\right(s)+2H^{+}(aq)\to Z{n}^{2+}(aq)+2H_{2}O(l)$
$Zn\left(OH{)}_2\right(s)+2O{H}^{-}(aq)\to [Zn\left(OH{)}_4{]}^{2-}\right(aq)$