In terms of physical changes, what is a common example of such a process?

The melting of ice is a classic example of a physical change because it involves a change in the state of matter without altering the chemical composition of the substance itself. When ice, which is solid water, melts, it transforms into liquid water as thermal energy is applied. This process is reversible; when the water cools down again, it can freeze back into ice. Therefore, the molecular structure of water remains unchanged whether it is in the solid, liquid, or gaseous state.

Other options, such as rusting of iron and burning wood, represent chemical changes. Rusting involves iron reacting with oxygen and moisture to form new substances like iron oxides, which cannot revert to the original iron. Burning wood is another chemical change, producing ash and gases, and changing the wood into completely different substances. Cooking an egg also leads to a chemical change, where the proteins in the egg undergo structural changes and cannot revert back to their raw state. In contrast, melting ice strictly changes its state and retains the same molecular structure, making it a quintessential example of a physical change.