Which of the following scenarios represents a physical change rather than a chemical change?

• A. Baking soda reacting with vinegar to produce bubbles
• B. Paper burning to produce ash and smoke
• C. Ice melting into liquid water
• D. Iron rusting when exposed to air

Answer: (C)

Verified step by step guidance

1. Understand the difference between physical and chemical changes: A physical change affects the form or state of a substance without changing its chemical identity, while a chemical change results in the formation of new substances with different chemical properties.
2. Analyze the scenario 'Baking soda reacting with vinegar to produce bubbles': This involves a chemical reaction producing new substances (carbon dioxide gas bubbles), so it is a chemical change.
3. Analyze the scenario 'Paper burning to produce ash and smoke': Burning paper results in new substances (ash, smoke, gases), indicating a chemical change.
4. Analyze the scenario 'Ice melting into liquid water': This is a change in the state of matter from solid to liquid without altering the chemical composition of water (H₂O), so it is a physical change.
5. Analyze the scenario 'Iron rusting when exposed to air': Rusting forms a new compound (iron oxide), which is a chemical change.