Carbon dioxide (CO₂) is an exemplary compound molecule composed of distinct molecules, unlike rusting or physical changes like the evaporation of water which do not produce compound molecules.
Carbon dioxide (CO₂) is an example of a compound molecule. Liquid nail polish hardening, ice melting to become water, exposed metal rusting, and water evaporating into the air are all processes that might involve chemical or physical changes, but they do not describe compound molecules themselves. Instead, compound molecules refer to distinct entities composed of two or more different elements.
In contrast, rusting is a chemical change where iron reacts with oxygen to form iron oxide. The hardening of nail polish involves the polymerization of compounds within the liquid nail polish. Evaporation and melting are physical changes, where substances change states without altering molecular composition.
In conclusion, carbon dioxide stands out as a clear example of a compound molecule because it consists of one carbon atom and two oxygen atoms chemically bonded together to form discrete molecules.