Chemistry - CHEMICAL BONDING Question with Solution | TestHub

Nitrogen (N) Atom: Due to $p\pi -d\pi$ back-bonding of its lone pair into the vacant $d$-orbitals of silicon, nitrogen adopts a planar geometry with sp² hybridization, giving it 3 hybrid orbitals.

Silicon (Si) Atoms: Each of the 3 silicon atoms forms four single $\sigma$-bonds (three with H and one with N), making them sp³ hybridized with 4 hybrid orbitals each.

Total Sum: Combining the hybrid orbitals from all atoms gives $3(fromN)+[3\times 4(fromSi)]=15$.