Question

Species acting as both Bronsted acid and base, is
(a) (HSO₄)⁻
(b) Na₂CO₃
(c) NH₃
(d) OH⁻

Answer 1

Species acting as both Bronsted acid and base, is (C) NH3.

Answer 2

a) HSO4-

A Bronsted acid is one which loses a proton to a stronger base

here HSO4 - loses H+ to give sulfate ion

A Bronsted base is one which accepts a H+ from a strong acid

here HSO4- accepts a H+ to form H2SO4