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

• A. A physical change can only occur at high temperatures, while a chemical change can occur at any temperature.
• B. A physical change involves breaking chemical bonds, while a chemical change does not.
• C. 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.
• D. A physical change always produces heat, while a chemical change does not.

Answer: (C)

Verified step by step guidance

1. Understand the definitions of physical and chemical changes: A physical change affects the form or appearance of a substance but does not alter its chemical identity, while a chemical change results in the formation of one or more new substances with different chemical properties.
2. Recognize that physical changes include changes in state (such as melting, freezing, or boiling) or shape, where the molecules remain the same and no new substances are formed.
3. Identify that chemical changes involve breaking and forming chemical bonds, leading to new substances with different compositions and properties (e.g., rusting, combustion, or digestion).
4. Evaluate the given options by comparing them to these definitions, focusing on whether the change affects chemical composition or just physical appearance.
5. Conclude that the best description is the one stating that a physical change alters appearance or state without changing chemical composition, whereas a chemical change produces new substances with different chemical properties.