What is an example of a reversible change?

Melting butter is an example of a reversible change because it can switch between solid and liquid states without altering its chemical composition. When butter melts, it transforms from a solid to a liquid due to heat, but once cooled, it solidifies back to its original form. This change can be repeated multiple times, making it reversible.

In contrast, cooking an egg results in a permanent change because the proteins in the egg undergo denaturation, leading to a new structure that cannot be undone. Freezing a plant leaf can also be considered a reversible change; however, it may likely cause damage to the leaf cells, thus not guaranteeing its viability when returned to normal conditions. Heating paper results in combustion, a permanent chemical change that cannot be reversed.