Phosphoric acid is a triprotic acid (3 acidic hydrogens) with ionization constants as follows: Ka1 = 7.5 x 10^-3 , Ka2 = 6.2 x 10^-8 , Ka3 = 4.2 x 10^-13 . Phosphate buffers with pH values near 2, 7, and 12 can be prepared using the appropriate ‘phosphate' conjugate acid-base pairs. Decide which of the following 2 solutions below you would use in order to prepare a phosphate buffer assigned by your instructor. Which is (12). Predict,using the Henderson-Hasselbalch equation, what this pH should be. A. 0.10 M phosphoric acid (H3PO4) B. 0.10 M sodium dihydrogen phosphate (NaH2PO4; the monobasic salt which contains H2PO4-ions) C. 0.10 M sodium hydrogen phosphate (Na2HPO4; the dibasic salt which contains HPO42-ions D. 0.10 M sodium phosphate (Na3PO4; the tribasic salt which contains PO43-ions)