Which of the following is a sign of a chemical change?

• A. Breaking a glass into pieces
• B. Dissolving sugar in water
• C. Change in state from solid to liquid
• D. Formation of a precipitate

Answer: (D)

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 form or state of a substance without changing its identity.
2. Analyze each option to determine if it represents a chemical or physical change:
3. - Breaking a glass into pieces is a physical change because the glass remains chemically the same, only its shape changes.
4. - Dissolving sugar in water is a physical change because sugar molecules disperse but do not chemically react or form new substances.
5. - Change in state from solid to liquid (melting) is a physical change because the substance's chemical identity remains unchanged.
6. Recognize that the formation of a precipitate indicates a chemical change because it involves the creation of a new solid substance from a solution, signaling a chemical reaction.