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

• A. Mass is neither created nor destroyed in a chemical reaction.
• B. The total number of atoms increases during a chemical reaction.
• C. Matter can be converted entirely into energy in ordinary chemical reactions.
• D. Energy is conserved during physical and chemical changes.

Answer: (A)

Verified step by step guidance

1. Understand that the law of conservation of mass states that in a chemical reaction, matter cannot be created or destroyed.
2. Recognize that this means the total mass of the reactants must equal the total mass of the products.
3. Note that the number of atoms remains constant during a chemical reaction, as atoms are simply rearranged to form new substances.
4. Eliminate options that suggest mass changes, such as the total number of atoms increasing or matter being converted entirely into energy, since these contradict the law.
5. Identify the correct description as: 'Mass is neither created nor destroyed in a chemical reaction.'