Aluminium is extracted from alumina (Al₂O₃) by electrolysis of a molten mixture of

Options

(a) Al₂O₃ + HF + NaAlF₄
(b) Al₂O₃ + CaF₂ + NaAlF₄
(c) Al₂O₃ + Na₃AlF₆ + CaF₂
(d) Al₂O₃ + KF + Na₃AlF₆

Correct Answer:

Al₂O₃ + Na₃AlF₆ + CaF₂

Explanation:

Electrolytic mixture contains alumina (Al₂O₃), cryolite (Na₃AlF₆) and fluorspar(CaF₂) in the ratio of 20 : 40 : 20. Due to presence of these conductivity of alumina increases and fusion temperature decreases from 2000⁰C to 900⁰C.