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

• A. Baking a cake
• B. Rusting of iron
• C. Melting of ice to form liquid water
• D. Burning of wood

Answer: (C)

Verified step by step guidance

1. Understand the difference between physical and chemical changes: A physical change affects the form or appearance of a substance but does not change 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 involves a change in chemical composition or just a change in physical state or appearance.
3. For 'Baking a cake,' recognize that this involves chemical reactions where new substances are formed, so it is a chemical change.
4. For 'Rusting of iron,' understand that iron reacts with oxygen to form iron oxide, a new substance, indicating a chemical change.
5. For 'Melting of ice to form liquid water,' note that this is a change of state from solid to liquid without altering the chemical identity of H2O, so it is a physical change.