Which change is an example of a physical change?

Chopping an apple exemplifies a physical change because it involves altering the physical form of the apple without changing its chemical composition. When you chop the apple, you are breaking it into smaller pieces, but the apple maintains its original molecular structure and properties. The flavor, color, and nutritional content remain the same.

In contrast, the other options represent chemical changes. Burning wood produces ash, gases, and other substances that are entirely different from the original material. Rust formation on iron involves a chemical reaction with oxygen and moisture, resulting in iron oxide, which is distinct from elemental iron. Baking a cake combines various ingredients that undergo chemical reactions when subjected to heat, resulting in new compounds with different flavors and textures. These examples illustrate that a physical change preserves the original substance, while a chemical change alters it.