A Diprotic Acid, H₂A, Has the Following Dissociation Constants

Multiple Choice

A diprotic acid, H₂A, has the following dissociation constants:
K_a1 = 2.1 x 10^-7 and K_a2 = 4.3 x 10^-13. The H₃O⁺ ion concentration when this acid is dissolved in water is

A) roughly equal to the H₂A concentration.
B) much larger than the H₂A concentration.
C) much larger than the HA^- concentration.
D) approximately equal to the HA^- concentration.
E) much less than the HA^- concentration.