In electrolysis of `A1_(2)O_(3)`by Hall-Heroult process:

Incorrect statement in electrolysis of Al_(2)O_(3) by Hall-Heroult process is :

Incorrect statement in electrolysis of Al_(2)O_(3) by Hall-Heroult process is :

In the extraction of Al by Hall-Heroult's process, electrolyte contains Na^+, Ca^(2+) and Al^(3+) . However only Al is discharged at cathode because,