Question

Nitrogen oxide which is paramagnetic is _________.

Answer 1

$NO$ : The oxidation state of $N$ is +2, and this is a colourless, paramagnetic gas (ie. it is a radical, or contains an unpaired electron). It plays an important role in the formation of ozone in the atmosphere.

$N{O}_2$ : The oxidation state of $N$ is +4. This exists in equilibrium between $N{O}_2$ and $N_2{O}_4$. $N{O}_2$ is a brown, paramagnetic gas (ie. it contains an unpaired electron), and $N_2{O}_4$ is a colourless, diamagnetic solid (ie. it contains only paired electrons).