The excess reactant is Aluminum.
Explanation:
We have to write the balanced equation as,
4 Al+ 3 O₂ → 2 Al₂O₃
According to the molar ratio 4: 3, from the given balanced equation, we can say that 4 atoms of Al reacted with 3 molecules of oxygen.
Given that 10 atoms of aluminum reacts with 6 molecules of oxygen, as per the ratio only 8 atoms of Aluminum is required to react with 6 molecules of oxygen, so excess reactant is Aluminum.
