Question

which of these chemical formulas - kcl, xe, co₂, h₂ - represents both an element and a molecule?
options: h₂, kcl, co₂, xe

Explanation:

An element is a pure substance with one type of atom; a molecule is a group of atoms bonded together. $\text{KCl}$ is an ionic compound (not a molecule/element). $\text{CO}_2$ is a molecule but a compound (two elements). $\text{Xe}$ is an element but a single atom (not a molecule). $\text{H}_2$ is an element (hydrogen) and a diatomic molecule.

Answer:

$\text{H}_2$