2.

The dissociation of the second proton from phosphate to form HPO42- has a pKa of 7.2. At pH 7.0 the relative concentrations of H3PO4, H2PO4- and HPO42- are

• a. [H3PO4] > [H2PO4-] > [HPO42-].
• b. [H3PO4] < [H2PO4-] > [HPO42-].
• c. [H3PO4] > [H2PO4-] > [HPO42-].
• d. [H3PO4] > [H2PO4-] < [HPO42-].
• e. [H3PO4] < [H2PO4-] < [HPO42-].