Which of the following best describes the law of conservation of mass?

• A. Energy and mass are always conserved together in every chemical reaction.
• B. The mass of products is always greater than the mass of reactants.
• C. Mass can be created or destroyed during a chemical reaction.
• D. The total mass of reactants equals the total mass of products in a chemical reaction.

Answer: (D)

Verified step by step guidance

1. Understand that the law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction.
2. Recognize that this means the total mass of the reactants before the reaction must be equal to the total mass of the products after the reaction.
3. Note that this law applies to all chemical reactions, ensuring that the amount of matter remains constant throughout the process.
4. Eliminate options that suggest mass can be created or destroyed, or that the mass of products is greater than reactants, as these contradict the law.
5. Conclude that the best description is: 'The total mass of reactants equals the total mass of products in a chemical reaction.'