Which is an example of a physical change?

Which is an example of a physical change?

• A. Baking a Cake
• B. Burning Wood
• C. Boiling an Egg
• D. Boiling Water

Answer: (D)

This question hinges on distinguishing physical changes from chemical changes by whether the substance’s identity changes. Boiling water is a physical change because you’re only changing its state from liquid to gas while the substance remains water (H2O). No new substance is formed, and the process is reversible by cooling. The other scenarios involve chemical transformations: baking a cake relies on chemical reactions that create new substances; burning wood produces ash, carbon dioxide, and other products; boiling an egg involves denaturation and coagulation of proteins, which are chemical changes. So boiling water best exemplifies a physical change.

This question hinges on distinguishing physical changes from chemical changes by whether the substance’s identity changes. Boiling water is a physical change because you’re only changing its state from liquid to gas while the substance remains water (H2O). No new substance is formed, and the process is reversible by cooling.

The other scenarios involve chemical transformations: baking a cake relies on chemical reactions that create new substances; burning wood produces ash, carbon dioxide, and other products; boiling an egg involves denaturation and coagulation of proteins, which are chemical changes. So boiling water best exemplifies a physical change.