Which one of the following elements corrodes rapidly?

Iron corrodes rapidly, because of its non-stable corrosion products on the surface. Rust occurs when metals containing iron react with the oxygen in the air or in water and form a compound called iron(III) oxide (ferric oxide). This compound contains water molecules, so we call it a hydrated compound. Both oxygen gas and water must be present for the iron to rust. Chemically and very simply speaking, iron atoms lose a few electrons to oxygen atoms. This process by which electrons are removed from atoms is called oxidation. When oxidation occurs, it produces a chemical reaction that creates iron(III) oxide-or rust.