(C) Cryolite is $Na_{3}AlF_{6}$.In the Hall-Heroult process,pure alumina $(Al_{2}O_{3})$ has a very high melting point $(2323 \ K)$ and is a poor cond

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$Na_{3}AlF_{6}$ and is used in the electrolysis of alumina for lowering the melting point and increasing the conductivity of alumina.

(C) Cryolite is $Na_{3}AlF_{6}$.In the Hall-Heroult process,pure alumina $(Al_{2}O_{3})$ has a very high melting point $(2323 \ K)$ and is a poor conductor of electricity.Cryolite $(Na_{3}AlF_{6})$ is added to the electrolyte to lower the melting point of the mixture to about $1240 \ K$ and to increase its electrical conductivity,making the electrolysis process more efficient.

Class 12 Chemistry General Principles and Processes of Isolation of Elements Reduction to free Metal

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Cryolite is

KCET 2015 All KCET

A
$Na_{3}AlF_{6}$ and is used in the electrolysis of alumina for decreasing electrical conductivity.
B
$Na_{3}AlF_{6}$ and is used in the electrolysis of alumina for lowering the melting point of alumina only.
C
$Na_{3}AlF_{6}$ and is used in the electrolysis of alumina for lowering the melting point and increasing the conductivity of alumina.
D
$Na_{3}AlF_{6}$ and is used in the electrolytic refining of alumina.