Which statement best describes the law of conservation of mass?

• A. Matter can be created from nothing during physical changes.
• B. Mass is neither created nor destroyed in a chemical reaction.
• C. The total number of atoms changes during a chemical reaction.
• D. Energy and mass are always interchangeable in chemical reactions.

Answer: (B)

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 atoms are simply rearranged during a chemical reaction, so the total number of atoms remains constant.
4. Distinguish this law from concepts related to energy, such as mass-energy equivalence, which is not part of the conservation of mass principle in chemistry.
5. Therefore, the best description is that mass is neither created nor destroyed in a chemical reaction.