Explanation:
A balanced chemical equation is the one that has same number of atoms present on both reactant and product side.
The balanced chemical reaction equation will be as follows.
According to law of conservation of mass, mass can neither be created nor it can be destroyed. It can only be transformed from one form to another.
Hence, total mass of reactant species in the above equation is 112.6 g. Hence, total mass of products is also 112.6 g.
Also, in this reaction Mg is present in solid state, is present in gaseous state, and MgO is present in solid state.
It has a decrease in oxidation number
The process of reduction is when the oxidation number of a chemical specie is lowered, or when the specie gains electrons. A chemical specie undergoing reduction will act as an oxidizing agent, because it will oxidize the other reactant by itself getting reduced.
The answer is C since both charge and mass have to be balanced on both sides of the equation.