Introduction:
Carbon cannot form metal aluminium from aluminium oxide due to the difference in their chemical properties. This can be explained by the following factors:

1. Carbon's reactivity:
Carbon is a non-metal and is not as reactive as metals like aluminium. It does not have the ability to reduce aluminium oxide to aluminium metal under normal conditions.

2. Redox potential:
The formation of metal from its oxide involves a reduction reaction, where the metal oxide is reduced to its elemental form. In the case of aluminium oxide, the reduction reaction requires a reducing agent with a higher redox potential than aluminium. Carbon, however, has a lower redox potential than aluminium and cannot effectively reduce aluminium oxide.

3. Thermodynamics:
The reduction of aluminium oxide to aluminium metal is an exothermic reaction, meaning it releases energy. In contrast, the conversion of carbon to carbon dioxide is an endothermic reaction, which requires an input of energy. Therefore, the thermodynamics of the reaction do not favor the formation of aluminium metal from aluminium oxide using carbon as a reducing agent.

4. Stability of carbon and aluminium oxide:
Carbon is a stable element and does not readily undergo chemical reactions. On the other hand, aluminium oxide is a stable compound and has a strong bond between aluminium and oxygen atoms. The strong bond in aluminium oxide makes it difficult for carbon to break the bond and replace oxygen to form aluminium metal.

Conclusion:
In conclusion, carbon cannot form metal aluminium from aluminium oxide due to its lower reactivity, redox potential, and stability compared to aluminium. The differences in their properties prevent carbon from effectively reducing aluminium oxide to aluminium metal.

Carbon has less reducing potential to attract shared pair of electron in free state or oxides .hence affinity of oxides increase bond enthalpy of higher reactive element and need large amount of energy to breakup electrovalent bond