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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.
