If ethene molecule is present on YZ plane then nodal plane of its $\mathrm{\pi }$ bond will lie on :

If ethene molecule is present on YZ plane then nodal plane of its $\mathrm{\pi }$ bond will lie on YZ plane and  molecular plane.

Nodal plane is the molecular plane.

A lack of electron density exists in the molecular plane. As a result, the molecular plane is where the nodal plane of the π  bond is placed. A plane parallel to the molecular plane is where  π electrons are located.

The nodal plane in ethene may be identified by the plane in the diagram.