Chapter 16, Problem 123SAE

The conjugate acid of ${\text{HPO}}_{\text{4}}^{\text{2-}}$ is (a) ${\text{PO}}_4^{2-}$ ; (b) ${\text{H}}_{\text{2}}{\text{PO}}_4^{-}$ ; (c) ${\text{H}}_{\text{2}}{\text{PO}}_{\text{4}}$ ; (d) $H_{2}O$ ; (e) none of these.