Solution:

Sub-atomic hydride is grouped based on the presence of the bonds and absolute number of electrons in their Lewis structures as:

Electron-inadequate hydrides

Electron-exact hydrides

Electron-rich hydrides

An electron-lacking hydride has exceptionally less electrons, not exactly that needed for addressing its traditional Lewis structure.

E.g

Diborane (B2 H6)

In B2 H6, there are 6 bonds altogether, out of which just 4 bonds are ordinary 2 focused 2 electron bonds.

The excess 2 bonds are 3 focused 2 electron bonds i.e., 2 electrons are shared by 3 molecules. Thus, its customary Lewis structure can’t be drawn.

By regular Lewis structure, an electron-exact hydride has an adequate number of electrons to be addressed.

for example CH4

The Lewis design can be composed as:

4 normal bonds are framed where 2 electrons are shared by 2 particles. An electron-rich hydride contains overabundance electrons as solitary sets.

for example NH3

There are 3 standard bonds in all with a solitary pair of electrons on the nitrogen molecule.