Which of the following best represents the law of conservation of mass in a chemical reaction?

• A. The total mass of reactants equals the total mass of products.
• B. The number of molecules increases during the reaction.
• C. Energy is created during the reaction.
• D. The mass of products is always greater than the mass of reactants.

Answer: (A)

Verified step by step guidance

1. Understand the law of conservation of mass: it states that mass cannot be created or destroyed in a chemical reaction.
2. Recognize that in a chemical reaction, atoms are rearranged but the total number of atoms remains the same.
3. Therefore, the total mass of all reactants before the reaction must equal the total mass of all products after the reaction.
4. Evaluate the given options by comparing them to this principle: the correct statement should reflect that the total mass remains constant.
5. Conclude that the option stating 'The total mass of reactants equals the total mass of products' best represents the law of conservation of mass.