Question

Which one of the following element shows amphoteric nature?

• A. B
• B. Al
• C. both Al and B
• D. Neither Al nor B

Answer 1

The correct option is B Al

Boron does not react with acids and alkalies even at moderate temperature.
Aluminium dissolves in mineral acids
and aqueous alkalies and thus shows its amphoteric nature.
$2Al\left(s\right)+6HCl\left(aq\right)\to 2A{l}^{3+}\left(aq\right)+6Cl\left(aq\right)+3H_2\left(g\right)$
Aluminium also reacts with aqueous
alkali and liberates dihydrogen.
$2Al\left(s\right)+2NaOH\left(aq\right)+6H_{2}O\left(l\right)\to 2N{a}^{+}\left[Al\right(OH{)}_4{]}^{-}\left(aq\right)+3H_2\left(g\right)\text{Sodium tetrahydroxoaluminate (III)}$