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

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

Answer: (A)

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 or physical change:
3. Formation of a precipitate indicates a chemical change because it shows a new solid substance forming from a solution.
4. Change in color often signals a chemical change as it can result from new substances with different properties being produced.
5. Production of a gas is a sign of a chemical change since it usually means a new gaseous substance is formed.
6. Change in state (such as melting or boiling) is a physical change because it only involves a change in the physical form (solid, liquid, gas) without altering the chemical composition.