What is a conjugate acid-base pair? Write
the conjugate acid and conjugate base of
each of the following
(a) OH^–
(b) ${\mathrm{HCO}}_3^{-}$

The acid base pair which are differentiated by one proton (${\mathrm{H}}^{\oplus }$) is called conjugate acid-base pair.
      Specie                Conjugate       conjugate
                                     acid                   base
(a) OH^–                       H₂O                   O^2–
(b) ${\mathrm{HCO}}_3^{-}$                H₂CO₃                ${\mathrm{CO}}_3^{2-}$