Which of the following is usually an indication of a chemical change?

• A. Breaking a glass
• B. Formation of a gas
• C. Melting of ice
• D. Dissolving sugar in water

Answer: (B)

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 creating new substances.
2. Analyze each option to determine if it represents a chemical or physical change:
3. - Breaking a glass is a physical change because the glass is only physically broken into pieces, but its chemical composition remains the same.
4. - Formation of a gas usually indicates a chemical change because it often results from a chemical reaction producing a new substance in the gaseous state.
5. - Melting of ice and dissolving sugar in water are physical changes because they involve changes in state or mixing without altering the chemical identity of the substances.