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

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

Answer: (A)

Verified step by step guidance

1. Step 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.
2. Step 2: Recognize that a chemical change involves a transformation that produces one or more new substances with different chemical properties and compositions.
3. Step 3: Identify that physical changes include changes in state (such as melting, freezing, or boiling) or shape, where the molecules remain the same.
4. Step 4: Note that chemical changes involve breaking and forming chemical bonds, leading to new substances, which is not the case in physical changes.
5. Step 5: Use these distinctions to evaluate the given statements and select the one that correctly contrasts physical and chemical changes based on changes in composition and substance formation.