What do you understand by $(i)$ electron deficient,$(ii)$ electron precise,and $(iii)$ electron rich compounds of hydrogen? Provide justification with suitable examples.

(N/A) Molecular hydrides are classified based on the number of electrons and bonds in their Lewis structures:
$(i)$ Electron-deficient hydrides: These have fewer electrons than required for writing a conventional Lewis structure. Example: Diborane $(B_{2}H_{6})$. Elements of group $13$ form such compounds and act as Lewis acids (electron acceptors).
$(ii)$ Electron-precise hydrides: These have the exact number of electrons required to write their conventional Lewis structures. Example: $CH_{4}$. Elements of group $14$ form such compounds,which typically exhibit tetrahedral geometry.
$(iii)$ Electron-rich hydrides: These have excess electrons present as lone pairs. Example: Elements of group $15-17$ form such compounds (e.g.,$NH_{3}$ has $1$ lone pair,$H_{2}O$ has $2$,and $HF$ has $3$ lone pairs). They act as Lewis bases (electron donors) and can form hydrogen bonds.