Answer:
It rusts
Explanation:
Iron is a chemical element that has the ability to RUST when exposed to air and water. Rusting is actually a prolonged chemical process or change that results when iron reactively combines with water and oxygen in the atmosphere to from hydrated (III) oxide in a process called OXIDATION. This compound is behind the color change of the metal.
According to this question, a nail made of iron will change after being exposed to the oxygen in the air over a long time by RUSTING via the oxidative reaction of the iron constituent of that nail with oxygen.
