Which compound below can act as both a brønsted-lowry acid and a brønsted-lowry base? a) hydrochloric acid b) ammonia c) sodium hydroxide d) water

Brønsted-Lowry acid is a specie which tends to donate H⁺, while Brønsted-Lowry base is a specie which tends to accepts H⁺. In Given compounds H₂O is a compound which can act as both acid and base.

As a Acid:
              When H₂O is reacted with strong base it acts as a acid, i.e donates H⁺ and forms OH⁻.

                            Base + H₂O   →   [Base-H]⁺  +  OH⁻

As a Base:
                 When H₂O is reacted with strong acid it accepts H⁺ and forms H₃O⁺ (Hydronium Ion), i.e.

                           Acid-H  +  H₂O   →   [Acid]⁻  +  H₃O⁺

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