* Diatomic molecule: Oxygen exists as a diatomic molecule, meaning it has two oxygen atoms bonded together.

* Equal electronegativity: Both oxygen atoms have the same electronegativity (the ability to attract electrons). This means they share the electrons in the bond equally.

* No net dipole moment: Since the electrons are shared equally, there is no separation of charge or partial charges on the molecule. This results in a zero net dipole moment.

Therefore, the oxygen molecule (O2) is nonpolar.