Which of the following is an indication that a chemical change has taken place?

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

Answer: (B)

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 chemically alter.
4. - Formation of a gas often indicates a chemical change because new gaseous products are formed from reactants.
5. - Change in state from solid to liquid is a physical change involving only a phase transition without altering chemical identity.
6. - Breaking a substance into smaller pieces is a physical change since the chemical composition remains the same.