The law of conservation of mass is best described as which of the following statements?

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

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 this law implies the number of atoms remains constant during a chemical reaction, although they may be rearranged.
4. Distinguish this from energy conservation, which is a separate principle stating that energy cannot be created or destroyed, only transformed.
5. Conclude that the correct description of the law of conservation of mass is: 'Mass is neither created nor destroyed in a chemical reaction.'