A student electrolyses copper(II) sulfate solution twice: first using graphite electrodes, then using copper electrodes.
Which observation is made only when graphite electrodes are used?
Bubbles of gas form at the positive electrode
A layer of copper forms on the negative electrode
The positive electrode loses mass
The blue colour of the solution stays the same
52 exam-style questions on OCR GCSE Chemistry 3.4 Electrolysis, covering 3.4.1 Products formed at the electrodes in electrolysis and 3.4.2 The technique of electrolysis. Each one has a worked solution and a mark scheme showing where the marks go.