A student sets up a cell using a magnesium electrode and a copper electrode in an electrolyte. The student measures the voltage every minute for one hour. The voltage slowly falls. Which statement explains why the voltage falls?
The copper electrode is slowly being used up in the reaction
The electrolyte in the cell is slowly turning into pure water
One of the reactants in the cell is slowly being used up
The two electrodes are slowly becoming the same metal
40 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.