Which of the following redox reactions take place?

I.     ${\text{C}}{{\text{l}}_2}{\text{(aq)}} + {\text{2NaI(aq)}} \to {{\text{I}}_2}{\text{(aq)}} + {\text{2NaCl(aq)}}$

II.     ${\text{B}}{{\text{r}}_2}{\text{(aq)}} + {\text{2NaI(aq)}} \to {{\text{I}}_2}{\text{(aq)}} + {\text{2NaBr(aq)}}$

III.     ${{\text{I}}_2}{\text{(aq)}} + {\text{2NaBr(aq)}} \to {\text{B}}{{\text{r}}_2}{\text{(aq)}} + {\text{2NaI(aq)}}$

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

A

One respondent stated that the wording of the question could have been better if it was stated which of the redox reactions are likely to occur, which is a fair point. The question was one of the more difficult questions on the paper, though 54% did manage to get the correct answer, namely A.