In the extraction of aluminium by Hall-Heroult process purified `Al_(2)O_(3)` is mixed with `CaF_(2)` to

Options

A. lower the melting point of `Al_(3)O_(3)`
B. increase the conductivity of molten mixture
C. reduce `AI^(3+)` into AI(s)
D. acts as catalyst

Answer

A, B

Explanation

(a,b) In the metallurgy of aluminium `Al_(2)O_(3)` is mixed with `Na_(3)AIF_(6)` and `CaF_(2)` which causes following affects.
(i) Lower the melting of `Al_(2)O_(3)` (ii) Increase the conductivity of molten mixture.