A buffer that is most effective at a pH of about 4.5 is:: (A) Acetate buffer, (B) Bicarbonate buffer, (C) Phosphate buffer, (D) Tris buffer
Answer is A. A buffer system becomes more effective when the pH of the system equals its pKa. Acetate buffer has a pKa value of 4.76 which nearly equals that of the system. So the buffer that is most effective at a pH of 4.5 is acetate buffer.