Which of the following is an example of a physical change?

• A. Rusting of iron to form Fe2O3
• B. Baking a cake
• C. Burning of methane (CH4) in oxygen
• D. Melting of ice to form liquid water

Answer: (D)

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 composition, while a chemical change results in the formation of new substances with different chemical properties.
2. Analyze the examples given: Rusting of iron, baking a cake, and burning methane all involve chemical reactions where new substances are formed, indicating chemical changes.
3. Focus on the example of melting ice: Melting ice to liquid water changes the state from solid to liquid but does not alter the chemical identity of H2O, so this is a physical change.
4. Recall that physical changes are usually reversible and involve changes in state, shape, or phase without breaking or forming chemical bonds.
5. Conclude that melting ice is a physical change because it involves a phase change without changing the molecular structure of water.