Which observation is a sign of a chemical change?

• A. Melting of ice into liquid water
• B. Formation of a gas when two solutions are mixed
• C. Breaking a glass into smaller pieces
• 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 only affects the state or appearance without changing the substance's identity.
2. Analyze each option to determine if it represents a chemical or physical change:
3. Melting of ice into liquid water is a physical change because it only changes the state from solid to liquid without altering the chemical composition of H\_2O.
4. Breaking a glass into smaller pieces is a physical change because the glass remains chemically the same, only its shape and size change.
5. Dissolving sugar in water is generally a physical change because sugar molecules disperse in water but do not chemically react to form new substances.
6. Formation of a gas when two solutions are mixed indicates a chemical change because the production of a gas suggests a chemical reaction has occurred, creating new substances.