What occurs during the operation of a voltaic cell based on the following overall reaction?

\[2{\text{A}}{{\text{g}}^ + }{\text{(aq)}} + {\text{Cu(s)}} \to {\text{2Ag(s)}} + {\text{C}}{{\text{u}}^{2 + }}{\text{(aq)}}\]

C

There were also two G2 comments on this question. One respondent stated that knowledge of this depth is off-syllabus. This is not correct. Both the movement of ions in solution and across a salt bridge should be covered in the programme. Candidates are expected to know this as part of their understanding of voltaic cells and ion movement has been asked previously in papers. 47.59% got the correct answer C. Although this was a common question with HL, certainly at SL the question was found to be more challenging and performance at HL was invariably better as discussed in the corresponding subject report for HLP1TZ2. At SL, the question was the seventh most difficult question on the paper and had an associated discrimination index of 0.46.