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General Principles And Processes Of Isolation Of Elements

Question
CBSEENCH12011144

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

Solution

C.

Al2O3 +Na3AlF6 +CaF2

Alumina, Al2O3, is a bad conductor of electricity and has a very high melting point, so before subjecting to electrolysis, it is mixed with fluorspar (CaF2) and cryolite (Na3AlF6), which lower its melting point and make it more conducting.