Question: which one of the following combinations will form a buffer solution?
Answer: A buffer is the combination of a weak acid or base and a salt of that weak acid or base. Buffers can be made from three combinations: (1) H 3PO 4 and H 2PO 4 −, (2) H 2PO 4 − and HPO 4 2−, and (3) HPO 4 2− and PO 4 3−. (Technically, a buffer can be made from any two components.)