Question

4 moles of MG in 5 moles of O2 find the moles of product and moles of accessing reagent after reaction

Answer 1

From the reaction equation, you see that the mole ratio of Mg to O₂ is 2:1, so 2 mol Mg would require 1 mol O₂. 5 mol O₂ are available, but there is only enough Mg to react with 1 mol of it. Therefore Mg is the limiting reactant.