Hydrogen gas is liberated when aluminium is treated with
A) Air
B) Dilute HCl (or) H₂SO₄
C) NaOH (or) KOH
D) conc. HNO₃

Aluminium dissolves in dilute HCl and liberates dihydrogen

$2{\mathrm{Al}}_{\left(\mathrm{s}\right)}+6{\mathrm{HCl}}_{\left(\mathrm{aq}\right)}\to 2{\mathrm{Al}}_{\left(\mathrm{aq}\right)}^{3+}+6{\mathrm{Cl}}_{\left(\mathrm{aq}\right)}^{-}+3{\mathrm{H}}_{2_{\left(\mathrm{g}\right)}}$

However, concentrated nitric acid renders aluminium passive by forming a protective oxide layer on the surface.
Aluminium also reacts with aqueous alkali and liberates dihydrogen.

$2{\mathrm{Al}}_{\left(\mathrm{s}\right)}+2{\mathrm{NaOH}}_{\left(\mathrm{aq}\right)}+6{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}\to \underset{\mathrm{sodium} \mathrm{tetrahydroxoaluminate}\left(\mathrm{III}\right)}{2{\mathrm{Na}}^{+}{\left[\mathrm{Al}{\left(\mathrm{OH}\right)}_4\right]}_{\left(\mathrm{aq}\right)}^{-}}+3{\mathrm{H}}_{2_{\left(\mathrm{g}\right)}}$

Aluminium forms a very thin oxide layer on the surface which protects the metal from further attack.

$2{\mathrm{Al}}_{\left(\mathrm{s}\right)}+3{\mathrm{O}}_{2_{\left(\mathrm{g}\right)}}\to 2{\mathrm{Al}}_2{\mathrm{O}}_{3_{\left(\mathrm{s}\right)}}$