Which of the following best explains why a state change from liquid to solid is not considered a chemical reaction?

• A. Because energy is not involved in the process of changing states.
• B. Because the chemical composition of the substance remains unchanged during the state change.
• C. Because the atoms rearrange to form new substances.
• D. Because the process always produces a gas as a product.

Answer: (B)

Verified step by step guidance

1. Understand the difference between a physical change and a chemical change. A chemical change involves the formation of new substances with different chemical compositions, while a physical change affects the form or state of a substance without altering its chemical identity.
2. Recognize that a state change from liquid to solid is a physical change because it involves a change in the arrangement and energy of particles, but the particles themselves remain chemically the same.
3. Recall that during freezing (liquid to solid), the molecules lose energy and arrange into a more ordered structure, but no new substances are formed and no chemical bonds are broken or formed.
4. Note that energy is involved in state changes (such as latent heat), so the statement 'Because energy is not involved' is incorrect.
5. Conclude that the best explanation is that the chemical composition remains unchanged during the state change, which is why freezing is not considered a chemical reaction.