In the metallurgy of aluminium,

Options

A. `Al^(3+)` is oxidised to `Al_((s))`
B. graphite anode is oxidised to carbon monoxide and carbon dioxide.
C. oxidation state of oxygen changes in the reaction at anode
D. oxidation state of oxygen change in the overall reaction involved in the process.

Answer

B

Explanation

The oxidation state of O does not change in either the reaction occurring at the anode or the overall reaction as shown below :
At anode :
`C + O^(2-) to overset(2+)Coverset(2-)O+2e^(-) , 2overset(2-)O to overset(4+)C overset(2-)O_(2)+4e^(-)`
At cathode : `Al^(3+) +3e^(-) to Al`
Overall reaction : `2overset(3+)(A_(2))overset(2-)(O_(3)) + 3C to 4Al + 3overset(2+)Coverset(2-)O_(2)`