H-A Is an Acid with a PKa of 4

Multiple Choice

H-A is an acid with a pKa of 4.5. Which of the following statements about an aqueous solution of H-A is true?

A) At pH = 4.5, the solution contains much more H-A than A^-
B) At pH = 4.5, the solution contains much more A^- than H-A
C) At pH- 3.5, the solution contains about 90% A^- and 10% H-A
D) At pH = 6.5, the soluton contains about 80% A^{- and 20% H-A}
E) At pH = 5.5, the solution contains about 90% A^- and 10% H-A