Question

Which ion is the conjugate base of `H_3PO_4`?

Answer 1

dihydrogen phosphate, `H_2PO_4^(2-)`

Explanation:

To find the conjugate base of any acid, simply remove one `H^+` ion from the formula of the base, and presto!

Conversely, to find the conjugate acid of any base, add `H^+` to the formula of that base.