\(PCl_5\) is well known but \(NCl_5\) is not because nitrogen does not have vacant d-orbitals in its valence shell.
So, nitrogen cannot expand its octet.
On the other hand phosphorus has vacant d-orbitals in its valence shell which enables it to expand its octet.
Therefore, the correct option is (B): nitrogen doesn’t have d-orbitals in its valence shell.
0.01 mole of an organic compound (X) containing 10% hydrogen, on complete combustion, produced 0.9 g H₂O. Molar mass of (X) is ___________g mol\(^{-1}\).