Chemistry · May / June 2016 · Paper 12 · Question 31

Aluminium is extracted from aluminium oxide by electrolysis. [diagram of electrolysis cell showing waste gases, carbon cathode (-ve), carbon anodes (+ve), purified aluminium oxide dissolved in molten cryolite, molten aluminium] Which statement about this electrolysis is correct?

1. AAluminium ions gain electrons to form aluminium.
2. BCryolite is added to increase the melting point of the electrolyte.
3. CCryolite is added to react with impurities to form slag.
4. DThe carbon cathode has to be replaced regularly as it reacts with oxygen.

As printed in the paper