Which of the following tasks in the kitchen is an example of a physical change?

• A. Melting butter in a pan
• B. Rusting of a steel knife
• C. Baking a cake
• D. Frying an egg

Answer: (A)

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 new substances with different properties.
2. Analyze each option to determine if the change involves altering the chemical composition or just the physical state:
3. Melting butter in a pan involves changing butter from solid to liquid without changing its chemical structure, so this is a physical change.
4. Rusting of a steel knife involves a chemical reaction between iron and oxygen to form iron oxide, which is a chemical change.
5. Baking a cake involves chemical reactions such as the Maillard reaction and the formation of new compounds, so it is a chemical change.
6. Frying an egg causes proteins to denature and new substances to form, indicating a chemical change.