(i) In aqueous solution, the hydronium ion is further hydrated to give species like ${\mathrm{H}}_5{\mathrm{O}}_2^{+},{\mathrm{H}}_7{\mathrm{O}}_3^{+}$ and ${\mathrm{H}}_9{\mathrm{O}}_4^{+}$.
(ii) The hydroxyl ion is hydrated to give several ionic species like ${\mathrm{H}}_2{{\mathrm{O}}_2}^{-2},{\mathrm{H}}_3{{\mathrm{O}}_3}^{-3}$ and ${\mathrm{H}}_4{{\mathrm{O}}_4}^{-4}$.