Chemistry - CHEMICAL BONDING Question with Solution | TestHub

$\mathrm{l}\mathrm{p}$ of $\mathrm{N}$ in $\mathrm{N}{\left(\mathrm{C}{\mathrm{H}}_3\right)}_3$ is free to donate while in $\mathrm{N}{\left(\mathrm{S}\mathrm{i}{\mathrm{H}}_3\right)}_3$ $\mathrm{l}\mathrm{p}$ is involved in back bonding so it is not easy to donate hence it is less basic.

Due to back bonding it is planar and ${\mathrm{sp}}^2$ hybridised.