Chapter 16, Problem 16.49SP

Which of the following can behave both as a Bronsted-Lowry acid and as a Bronsted-Lowry base?

(a) ${\text{HCO}}_{\text{3}}{}^{-}$

(b) ${\text{CN}}^{\text{-}}$

(c) ${\text{H}}_{\text{2}}O$

(d) ${\text{H}}_{\text{2}}{\text{CO}}_{\text{3}}$