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

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

Answer: (C)

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. - Dissolving sugar in water is a physical change because the sugar molecules disperse but do not change chemically.
4. - Breaking a glass into smaller pieces is a physical change because the glass's chemical composition remains the same.
5. - Formation of a gas typically indicates a chemical change because new substances are produced, often involving gas evolution.
6. - Change in state from solid to liquid (melting) is a physical change because the substance's chemical identity remains unchanged.