Which of these chemical formulas kci, xe, co2, or h2 - represents both an element and a molecule?

An element is a substance that can not be broken into simpler parts by chemical means. Elements are made up of atoms. A molecule is the smallest particle of an element or a compound that has the same properties as the element or the compound. A molecule is made up of two or more atoms. A substance may be an element and a molecule. In this case the answer is, H2 (hydrogen gas) which is a molecule with two atoms of hydrogen and an element.