Which of the following must occur during a chemical change?

• A. Change in physical state only
• B. Formation of one or more new substances
• C. Change in temperature without altering chemical composition
• D. Separation of mixtures into their components

Answer: (B)

Verified step by step guidance

1. Understand that a chemical change involves the transformation of substances into new substances with different chemical properties and compositions.
2. Recognize that a change in physical state (such as melting or boiling) is a physical change, not a chemical change, because the chemical composition remains the same.
3. Note that a change in temperature without altering chemical composition is a physical change, as no new substances are formed.
4. Identify that separation of mixtures into their components is a physical process, not a chemical change, since the substances themselves do not change chemically.
5. Conclude that the key characteristic of a chemical change is the formation of one or more new substances, which distinguishes it from physical changes.