The nitrogen valence shell is L –shell. L shell doesn't hold d-orbitals, so Nitrogen doesn't have vacant d-orbitals, so it cannot form expanded octet configuration. So, Nitrogen is unable to give pentahalides, Nitrogen only forms trihalides.

Why does nitrogen form Pentahalides?

Nitrogen cannot increase its coordination number beyond four due to the absence of d-orbitals in its valence shell. ... Phosphorus forms pentahalides because it has vacant d-orbitals to extend its octet.

Which of the following does not form a Pentahalide?

Nitrogen does not form pentahalide because it can not extend its valency upto 5 due to unavailability of d orbitals.