Classify molecular hydrides. Explain each type with two examples.

(N/A) Molecular hydrides are classified based on the relative number of electrons and bonds in their Lewis structures as follows:
$(i)$ Electron-deficient hydrides: These hydrides contain fewer than eight electrons around the central atom.
$\rightarrow$ Group-$13$ elements form these hydrides. Examples: $BH_{3}$,$AlH_{3}$.
- These hydrides act as Lewis acids.
$(ii)$ Electron-precise hydrides: In these hydrides,the central atom has exactly eight electrons. Group-$14$ elements form these hydrides. Examples: $CH_{4}$,$SiH_{4}$.
$(iii)$ Electron-rich hydrides: In these hydrides,the central atom has lone pairs of electrons,resulting in more than $8$ electrons in the valence shell. Group-$15$,$16$,and $17$ elements form these hydrides. Examples: $NH_{3}$,$H_{2}O$.