# What is the conjugate base of "phosphoric acid", H_3PO_4?

${H}_{2} P {O}_{4}^{-}$
The conjugate acid of a base is the original species PLUS a proton, ${H}^{+}$. The conjugate base of an acid is the origianl species LESS a proton. Both MASS and CHARGE are conserved.
What are the conjugate bases of $H P {O}_{4}^{2 -}$, and $H S {O}_{4}^{-}$?