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The major role of fluorspar (CaF2), whic...

The major role of fluorspar `(CaF_2)`, which is added in small quantities in the electrolytic reduction of alumina dissolved in fused cryolite `(Na_3AIF_6)`, is

A

As a catalyst

B

To make the fused mixture very conducitng

C

To increase the temperature of the melt

D

To decrease the rate of oxidation of carbon at the anode

Text Solution

Verified by Experts

The correct Answer is:
B
Pure alumina is a bad conductor of electricity. The fusion temperature is about `2000^@ C`. When electrolysis is carried out on the fused mass, the metal formed vaporises (boiling point ofaluminium is `1800^@C` ). These difficulties are overcome byusing a mixture containing alumina, cryolite `(Na_(2) AlF_(6))`and fluorspar
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