Phosphoric acid H3PO4 is a triprotic acid for which Ka1=7.2 x10-3 Ka2 = 6.3 x 10

Phosphoric acid H3PO4 is a triprotic acid for which Ka1=7.2 x10-3 Ka2 = 6.3 x 10-8 and Ka3 = 4.2x 10-13. What is the value ofKb for hydrogen phosphate anion HPO4 2-? a. 6.3 x 10-8 b. 4.2 x10-13 c. 1.4 x 10-12 d. 1.6 x 10-7 e. 2.4 x 10-2