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

Among the four choices of chemical formula listed above, we are tasked to find that represents both a molecule and the elements. Using elimination method, KCl and CO2 is not anymore part of the choices since it is a compound leaving Xe and H2. H2 is a hydrogen gas and a compound. Therefore the correct answer to the problem above is Xe. Xe can be access in the modern periodic table, thus, it is an element.

Yes you are correct use the scientific method

Talc (french chalk) is the ingredient