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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3mt161

Which statements about the Hall-Heroult process are correct?

Afluorspar, $CaF X_{2}$ , is added to lower the melting point and improve the fluidity of the melt
Bthe overall cell reaction is $2 Al X_{2} O X_{3} + 3 C 4 Al + 3 CO X_{2}$
Cliquid aluminium is liberated at the anode and floats on the melt
Dthe steel tank lined with graphite acts as the cathode

Answer: A, B, D

The graphite-lined tank is the cathode where

Al X^{3 +}

is reduced and the molten metal collects at the bottom. Fluorspar lowers the melting point. The overall reaction consumes graphite anodes giving

CO X_{2}

. Aluminium is formed at the cathode, not at the anode, and being denser than the melt it sinks.

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