A mineral-processing laboratory prepares two aqueous solutions containing ions of unidentified metals P and Q.
The P-ion solution is electrolysed using inert electrodes. A solid layer of P forms at the cathode.
Metal Q is less reactive than metal P. The Q-ion solution is then electrolysed using inert electrodes.
Which prediction about the electrolysis of the Q-ion solution is correct?
Hydrogen forms at the cathode because Q is less reactive than P.
Both Q and hydrogen form because both positive ions move to the cathode.
Oxygen forms at the cathode because hydroxide ions are present in the solution.
Q forms at the cathode because Q is less reactive than hydrogen.
98 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.