A substance is called amphoteric if it displays characteristics of both acids and bases. Aluminium dissolves in both acids and bases, showing amphoteric behaviour.
(i)`2Al_((s))+6HCl_((aq))rarr2Al_((aq))^(3+)+6Cl_((aq))^(-)+3H_(2(g))`
(ii)`2Al_((s))+2NaOH_((aq))+6H_(2)O_((l))rarr2Na^(+)[Al(OH)_(4)]_((aq))^(-)+3H_(2(g))`
