(D) HF and NaOH (D) This will form a buffer if you have half as much NaOH as HF. When you neutralize HF with NaOH, you form F-, the conjugate base of HF. 1997-36. (A) HF and NaF – classic weak acid (HF) and its conjugate base (F-) Notice the question states “equal numbers of moles of each”.