(i) lower the melting point of Al2O3
(ii) increase the conductivity of molten mixture.
(iii) reduce Al3+ into Al(s).
(iv) acts as a catalyst
Correct Answers:
(i) lower the melting point of Al2O3
(ii) increase the conductivity of molten mixture.
Explanation: In the extraction of aluminium by Hall-Heroult process, purified Al2O3 is mixed with CaF2 to lower the melting point of Al2O3 and to increase the conductivity of molten mixture.