Emmaxox5614 Emmaxox5614 09-12-2022 SAT contestada Phosphoric acid is tribasic, with pKa's of 2.14, 6.86, and 12.4. The ionic form that predominates at pH3.2 is: A) H3PO4. B) H2PO4-. C) HPO42-. D) PO43-. E) none of the above.