According to the Law of Conservation of Mass, which of the following is conserved during a chemical reaction?

• A. The total mass of the reactants and products
• B. The number of molecules of each substance
• C. The volume of the system
• D. The temperature of the reactants

Answer: (A)

Verified step by step guidance

1. Understand the Law of Conservation of Mass, which states that mass cannot be created or destroyed in a chemical reaction.
2. Recognize that this law implies the total mass of the reactants before the reaction must equal the total mass of the products after the reaction.
3. Note that the number of molecules of each substance is not necessarily conserved because molecules can be rearranged or transformed into different substances.
4. Understand that volume and temperature are physical properties that can change during a reaction and are not conserved according to this law.
5. Conclude that the correct conserved quantity according to the Law of Conservation of Mass is the total mass of the reactants and products.