If the filling of electrons in the molecular orbital of ${\mathrm{O}}_2$ does not obey Hund's rule then which of the following property in ${\mathrm{O}}_2$ gets changed?
 

A magnetic moment has a direction and a magnitude, making it a vector quantity. Due to its inherent spin feature, an electron possesses a magnetic dipole moment, which causes it to be an electric charge in motion. There are several varieties of magnetic behavior, such as ferromagnetism, diamagnetism, and paramagnetic.

Hence, the option B is correct.