Chemistry Question

Carbon can reduce the metal oxide back to its metallic state because of its reducing power.
2MO + C = 2M + CO2
However, carbon can only reduce the metals which has lower reducing power than carbon. Sinec magnesium has a more negative reduction potentail, in another words, magnesium is more reducing than carbon, heating carbon with magnesium oxide canot convert the magnesium back to metallic magnesium.

MgO cannot be extractes by heating their oxides with carbon because MgO is an ionic compound.Therefore , cations and anions held by strong electrostatic force . Also , Mg at the high position in E.C.S. the attraction force between the ions are larger than the metal at the lower position in E.C.S.
You can extracted Mg from MgO by eletrolytes .4 more metal oxides also extracted by eletrolytes , they are Potassium , Sodium , Calcium and Aluminium.