Identify the acid/conjugate base and base/conjugate acid pairs for the following reactions

Question

H2CO3(aq) + H2O(l) <===> H3O+(aq) + HCO3
-(aq)

C5H5N(aq) + H2O(l) <===> C5H5NH+(aq) + OH-(aq

Answer 1

H2CO3(aq) + H2O(l) <===> H3O+(aq) + HCO3
H2O accepted a proton to become (H3O^+; therefore it must be the base and H3O^+ the conjugate acid.
H2CO3 gave a H away to H2O, therefore, H2CO3 must be the acid in this reaction and HCO3^- must be the conjugate base (what's left of the acid is the base).