<prompt> Which of the following is the most effective buffer for pH of 7.4?Carbonic acid buffer with pKA-6.1Phosphate buffer with pKA of 6.9Glutamate buffer with pKA-8.7Acetate buffer with pKa 4.5  <response>: Blood pH - 7.4 Buffer is most effective when pH pKA - 1 Therefore the most effective buffer for pH- 7.4 will be the one whose pKA - 1 will cover this pH. Out of given options pKA - 1 of phosphate buffer 5.9 to 7.9 covers pH 7.4. So most effective buffer for blood will be Phosphate buffer with pKA of 6.9. 