4. Which of the following statements are NOT TRUE regarding the properties of a buffer solution? (1) A buffer is a mixture of a weak acid and its conjugate base. (2) A buffer resists pH changes when acids or bases are added. (3) The maximum capacity of the buffer is at pH = pKa. (4) The pH of a buffer is independent on the solution ionic strength and temperature. (5) A buffer made from a diprotic acid should not be treated in the same way as a buffer made from a monoprotic acid. Your answer:
(A) (2), (4) and (5)；
(B) (1), (2) and (3)；
(C) (1),(3) and (4)；
(D) (4) and (5)；
(E) The statements are all true.