Amphoteric nature of water is represented by following chemical reactions.(1) Water as a base:\\\\(\\displaystyle H_2O(l)+H_2S(g) \\rightleftharpoons H_3O^+(aq) + HS^-(aq) \\\\)(2) Water as an acid:\\\\(\\displaystyle H_2O(l) + NH_3(aq) \\rightleftharpoons OH^-+NH_4^+ \\\\)(3) Self ionization of water in which water simultaneous acts as acid and base.\\\\(\\displaystyle 2H_2O \\rightarrow H_3O^+ + OH^- \\\\)