Why is nitric oxide $(NO)$ paramagnetic in the gaseous state,but the solid obtained on cooling it is diamagnetic?

(N/A) Nitric oxide $(NO)$ is an odd-electron molecule with a single unpaired electron on the nitrogen atom,represented as $: \dot{N}=\ddot{O}$.
Due to this unpaired electron,$NO$ is paramagnetic in the gaseous state.
In the solid state,however,$NO$ molecules undergo dimerization to form $N_2O_2$,where the unpaired electrons pair up,making the solid diamagnetic.