A solution contains 2x10-3 mol/L of a weak acid (pK=3.5) and 2x10-3 mol/L of its conjugate base. Its pH is best approximated by which one of the following?

Buffers consist of solutions of acid-base conjugate pairs, such as acetic acid and acetate.a. Near its pK, a buffer maintains the pH of a solution, resisting changes due to addition of acids or bases. For a weak acid, the pK is often designated as pKa .b. At the pKa , and are equal, and the buffer has its maximal capacity.The pH and pK are related as follows: pH=pK+log(/). Thus, when the concentrations of a weak acid and its conjugate base are equal, the pH equals the pK. The pK is defined as the pH at which =