Chemistry · EQUILIBRIUM

Consider the following statements regarding polyprotic acids and acid-base equilibria: (A) Higher order ionization constants of a polybasic acid are always smaller than the first ionization constant (\( K_{a_1} > K_{a_2} > K_{a_3} \)). (B) It is electrostatically more difficult to remove a positively charged proton from a negatively charged anion than from a neutral molecule. (C) In a mixture of a diprotic acid \( \text{H}_2\text{A} \) and water, the primary concentration of \( \text{H}_3\text{O}^+ \) is governed mainly by the second ionization step. (D) For carbonic acid, \( K_{a_1} = 4.3 \times 10^{-7} \) and \( K_{a_2} = 5.6 \times 10^{-11} \), so the predominant species containing carbon at \( \text{pH} = 9 \) is \( \text{HCO}_3^- \). Which of the above statements are correct?

1. A
   (A), (B) and (C) only
2. B
   (A) and (D) only
3. C
   (B), (C) and (D) only
4. D
   (A), (B) and (D) only