Why is nitric oxide paramagnetic in gaseous state but the solid obtained on cooling it is diamagnetic ?

Explanation

NO has odd no. of electrons `(7+8=15)` and due to the presence of unpaired electron, it is paramagnetic in the gaseous state. However, in the liquid and solid states, the unpaired electrons are involved in the formation of loose dimer. In the absence of any unpaired electron, it is diamagnetic in nature.