Final answer:
According to the law of conservation of mass, the total mass of atoms must stay the same on both sides of a balanced chemical equation, ensuring matter is neither created nor destroyed.
Step-by-step explanation:
According to the law of conservation of mass, the aspect that remains the same on both sides of a balanced chemical equation is C. the total mass of atoms. This law states that the mass of the reactants in a chemical reaction must equal the mass of the products, thus the same number of each type of atom must appear on each side of the equation. This consistency of mass ensures that matter is neither created nor destroyed in the reaction. The coefficients and subscripts in a balanced equation will adjust so that the consensus on both sides of the reaction remains equal in terms of the total mass of the atoms involved.