Which of the following is NOT an example of a physical change?

• A. Dissolving sugar in water
• B. Boiling of water
• C. Melting of ice
• D. Burning of magnesium ribbon

Answer: (D)

Verified step by step guidance

1. Step 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 new substances with different properties.
2. Step 2: Analyze each option to determine if it involves a change in chemical composition or just a change in physical state or form.
3. Step 3: Dissolving sugar in water is a physical change because sugar molecules disperse in water but do not change chemically.
4. Step 4: Boiling of water and melting of ice are physical changes because they involve changes in the state of water (liquid to gas, solid to liquid) without altering the chemical identity of H2O.
5. Step 5: Burning of magnesium ribbon is a chemical change because it involves a reaction with oxygen to form magnesium oxide, a new substance with different chemical properties.