<prompt> A solution contains 2x10-3 molL of a weak acid pK3.5 and 2x10-3 molL of its conjugate base. Its pH is best approximated by which one of the following?4.13.93.53.1  <response>: 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: pHpKlog. 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 