In the reaction , the substance oxidised is-

Correct option is B

The correct answer is (b) Carbon monoxide.
· In the reaction MgO+CO→Mg+CO2MgO + CO , carbon monoxide (CO) is the substance that gets oxidized. It is oxidized to carbon dioxide (CO2) by gaining an oxygen atom. Oxidation refers to the loss of electrons or an increase in oxidation state, often accompanied by the gain of oxygen.
Explanation:
· Oxidation of CO: CO→CO2​. Here, carbon in CO has an oxidation state of +2, which increases to +4 in CO2​.
· Reduction of MgO: MgO→Mg. Here, magnesium in MgO is reduced from an oxidation state of +2 to 0.