Which statement about physical changes is true?

• A. They always involve a chemical reaction
• B. They produce new substances
• C. They occur only at high temperatures
• D. They do not form new substances

Answer: (D)

Physical changes involve changes in form or state without changing the substance’s chemical identity. For example, ice melting to water or sugar dissolving in water changes how it looks or moves, but the chemical formula stays the same. Because no new substances are formed, these changes are not chemical reactions. The other statements are not correct: chemical reactions aren’t required for physical changes, physical changes don’t produce new substances, and they don’t only occur at high temperatures. So, the statement that physical changes do not form new substances is true.