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

• A. Melting of ice
• B. Formation of a precipitate
• C. Change in physical state without new substance formation
• D. Dissolving sugar in water

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. Melting of ice is a physical change because it involves a change in state from solid to liquid without forming a new substance.
4. 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.
5. Dissolving sugar in water is a physical change since the sugar molecules disperse in water but do not chemically react to form a new substance.