Which of the following best describes what happens when a substance undergoes a physical change?

• A. The substance forms new chemical compounds with different properties.
• B. The substance changes its physical appearance but its chemical composition remains the same.
• C. The atoms within the substance are rearranged to create new elements.
• D. The substance is always converted into a gas.

Answer: (B)

Verified step by step guidance

1. Understand the definition of a physical change: it is a change that affects the form or appearance of a substance but does not alter its chemical composition.
2. Recognize that during a physical change, the molecules or atoms of the substance remain the same; no new substances or chemical compounds are formed.
3. Note that physical changes can include changes in state (such as melting, freezing, or boiling), shape, or size, but the identity of the substance remains unchanged.
4. Contrast this with a chemical change, where the substance's chemical composition changes and new substances with different properties are formed.
5. Therefore, the best description of a physical change is that the substance changes its physical appearance but its chemical composition remains the same.