My question is:
Classify each species as in the following reactions as an acid or a base, and connect each conjugate pair:
H3PO4 + OH --- H2PO4 + H2O
H2PO4 + OH --- HPO4 + H2O
HPO4 + OH --- PO4 + H2O
I think that the reactions are all bases, but I don't understand what is meant by "connect" each conjugate pair.