Is Oxygen Paramagnetic or Diamagnetic?

Hint: We know that the molecular orbital theory, the molecular orbital structure of oxygen contains two unpaired electrons in the antibonding orbitals. The molecule having unpaired electrons in the configuration is known as paramagnetic in nature.

Complete answer:
Oxygen is paramagnetic chiefly as a result of it consisting of two unpaired electrons in its last molecular orbital. This may be well-tried if we glance at the molecular orbital diagram of oxygen. If we have a tendency to fill every orbital as per Hund’s rule we'll see that oxygen may be a radical having two unpaired electrons with constant spin. Meanwhile, if we glance at electrons they do not solely go round the atom in their orbitals however they additionally tend to spin making some variety of a field. As such, once there are unpaired electrons like in oxygen they spin within the same direction generating a bigger field impact and giving \[{{O}_{2}}\] its paramagnetic characteristic. Paramagnetic species have unpaired electrons while the diamagnetic species have all electrons paired up.
So, from above the Oxygen atom has eight as the total number of electrons. The unpaired or paired electrons are decided on the basis of filling up of orbitals. The paramagnetic species are those which have unpaired electrons in any subshell of the orbital while the diamagnetic species have all the electrons paired up. We have one atom, say oxygen, then we will talk about electronic configuration. And in this the subshells, shells and orbitals are filled accordingly while in case of molecules which consists of at least two atoms; we talk about its molecular orbitals.

Note:
Remember that the molecular orbital theory can explain the existence of molecules on the basis of bond order, this holds good for diatomic molecules but not for the polyatomic molecules. Also, only with the help of molecular orbital theory one cannot describe the geometry and shape of the molecule.