The correct statement regarding a chemical reaction is:
The total number of atoms does not change, so mass is conserved in the reaction.
This is based on the law of conservation of mass, which states that in a closed system, mass is conserved during a chemical reaction, meaning that the total mass of the reactants equals the total mass of the products. Since atoms are not created or destroyed in a chemical reaction, the number of atoms remains the same before and after the reaction.