Here's why:
* Bent geometry: The molecule has a bent shape due to the presence of a lone pair on the nitrogen atom.
* Symmetry elements:
* C2 axis: A rotation by 180 degrees about an axis passing through the nitrogen atom and bisecting the O-N-O angle.
* Two vertical mirror planes (σv): One plane containing the nitrogen atom and the two oxygen atoms, and another perpendicular to this plane and passing through the nitrogen atom.
* No horizontal mirror plane (σh): There is no plane of symmetry perpendicular to the C2 axis.
These symmetry elements define the C2v point group.
