A field laboratory compares four simple cells for use in a water-quality sensor. Each cell contains the same electrolyte and is tested under the same conditions.
| Cell | Metal electrodes | Voltage in V |
|---|---|---|
| P | magnesium and copper | 1.8 |
| Q | zinc and silver | 1.6 |
| R | iron and silver | 1.2 |
| S | zinc and iron | 0.3 |
Which cell contains the pair of metals with the smallest difference in reactivity?
Cell P: magnesium and copper
Cell Q: zinc and silver
Cell R: iron and silver
Cell S: zinc and iron
90 exam-style questions on AQA GCSE Chemistry 5.2 Chemical cells and fuel cells, covering 5.2.1 Cells and batteries, 5.2.2a Fuel cells, and 5.2.2b Half equations for hydrogen fuel cells. Each one has a worked solution and a mark scheme showing where the marks go.