Which of the following is NOT a possible sign of a chemical change?

• A. Change in color
• B. Change in state (such as melting or boiling)
• C. Production of a gas
• D. Formation of a precipitate

Answer: (B)

Verified step by step guidance

1. Understand that a chemical change involves the formation of new substances with different properties, while a physical change affects only the state or appearance without changing the substance's identity.
2. Review each option to determine if it indicates a chemical change or a physical change:
3. Change in color can indicate a chemical change because it may result from the formation of new substances with different colors.
4. Production of a gas is often a sign of a chemical change, as it suggests a new substance is being formed and released.
5. Formation of a precipitate (a solid formed from a solution) is a classic indicator of a chemical change because it shows new substances are created.
6. Change in state (such as melting or boiling) is a physical change, not a chemical change, because the substance changes its physical form but remains chemically the same.