Aluminium is extracted from alumina (Al2O3) by electrolysis of a molten mixture of
- Al2O3 + HF + NaAlF4
- Al2O3 + CaF2 + NaAlF4
- Al2O3 + Na3AlF6 + CaF2
- Al2O3 + KF + Na3AlF6
Answer
(3) Al2O3 + Na3AlF6 + CaF2
Solution
As per NCERT (Hall–Héroult process), purified Al2O3 is mixed with Na3AlF6 (cryolite) or CaF2 (fluorspar), which lowers the melting point of the mixture and increases its conductivity.
The molten mixture is Al2O3 + Na3AlF6 + CaF2.
Answer: (3)