Write chemical reactions taking place in the extracion of Aluminium from Bauxite ore .

Options

A. The concentration of ore is done by gravity separation method.
B. molten mixture of aluminium oxide, cryolite or fluorspar is electrolysed
C. impure aluminium is refined by liquation
D. molten aluminium is obtained at cathode while fluorine is liberated at anode.

Answer

B

Explanation

Purified `Al_(2)O_(3)` is mixed with `Na_(3)AlF_(6)` and `CaF_(2)` to improve conductivity of `Al_(2)O_(3)` and to lower than melting point.
`Al_(2)O_(3) overset("electrolysis")to 2Al^(3+) + 3O^(2-)`
At cathode `: AL^(3+)+3e^(-) to Al`
At anode :` C + O^(2-) to CO + 2e^(-) `
`C+2O^(2-) to CO_(2) + 4e^(-)`