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.
the cardiovascular system includes your heart and blood vessels, which function to remove deoxygenated blood from and return oxygenated blood throughout your body
