How does the pKa of a buffering agent relate to its effectiveness at a particular pH?

• A. A buffer is most effective when the pKa is much higher than the pH.
• B. A buffer is most effective when the pKa is equal to or close to the pH.
• C. A buffer is most effective when the pKa is much lower than the pH.
• D. The pKa does not affect the buffer’s effectiveness at a particular pH.

Answer: (B)