Answer : The balanced chemical reaction will be,

Explanation :
Balanced chemical reaction : It is the reaction in which the number of atoms of an individual elements present on reactant side must be equal to the product side.
As per question, when 2 moles of magnesium react with 1 mole of oxygen the it reacts to give 2 moles of magnesium oxide as a product.
The balanced chemical reaction will be,
