* No new substance is formed: The nail varnish simply coats the nail. The chemical composition of the nail and the nail varnish itself doesn't change.
* The change is easily reversible: You can remove the nail varnish with nail polish remover, and the nail returns to its original state. While some staining can occur, the fundamental composition of the nail remains unchanged.
* Only the appearance changes: The main effect of applying nail varnish is to change the color and texture of the nail surface.
In contrast, a chemical change involves the formation of a new substance with different properties. Examples of chemical changes would include rusting of iron or burning wood.