Which of the following is an indicator that a chemical change has occurred?

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

Answer: (D)

Verified step by step guidance

1. Understand the difference between physical and chemical changes: A physical change affects the form of a substance but not its chemical composition, while a chemical change results in the formation of one or more new substances with different properties.
2. Analyze each option to determine if it represents a physical or chemical change:
3. - Change in state from solid to liquid is a physical change because the substance's chemical identity remains the same.
4. - Dissolving sugar in water is a physical change since sugar molecules disperse but do not chemically alter.
5. - Breaking a glass into smaller pieces is a physical change because the glass's chemical composition is 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 has occurred.