Which mixtures could act as buffers?

I.     NaOH(aq) and HCl(aq)

II.     NaOH(aq) and \({\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH(aq)}}\)

III.     HCl(aq) and \({\text{C}}{{\text{H}}_{\text{3}}}{\text{COONa(aq)}}\)

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

C

One respondent stated that this question was fair but tricky. However, this question is based on the syllabus, as stated in AS 18.2.2. In the teachers notes on buffers, selected examples are given. It should be emphasized that buffer solutions should not be confined solely to these examples but these examples should be included in the teaching programme.