Which statement best describes the difference between a physical change and a chemical change?

• A. A chemical change can be easily reversed, but a physical change cannot.
• B. A physical change only occurs at high temperatures, whereas a chemical change occurs at any temperature.
• C. A physical change always involves the production of heat, while a chemical change does not.
• D. A physical change alters the appearance or state of a substance without changing its chemical composition, while a chemical change results in the formation of new substances with different chemical properties.

Answer: (D)

Verified step by step guidance

1. Understand the definitions: A physical change affects the form or appearance of a substance but does not alter its chemical composition, meaning the molecules remain the same.
2. Recognize that a chemical change involves a transformation where new substances with different chemical properties and compositions are formed, indicating a rearrangement of atoms.
3. Identify examples of physical changes such as melting, freezing, or dissolving, where the substance can often be returned to its original state without changing its identity.
4. Identify examples of chemical changes such as combustion, rusting, or digestion, where the original substances are converted into new substances and the change is usually not easily reversible.
5. Conclude that the key difference lies in whether the chemical composition changes (chemical change) or remains the same (physical change), which aligns with the correct answer provided.