Answer the question on the basis of passage given below:
Second period elements of p-Block differ from the rest of their group members due to their small atomic size, high electronegativity, high ionization enthalpy and absence of d-orbitals.
The elements from the second period like C, N, O have unique property of forming pπ–pπ multiple bonds whereas other heavier elements of p-block form dπ–pπ multiple bonds. This changes the properties of second period elements to great extent. Also the single bond strength of the p-block elements with their own atoms gets affected by their atomic size and presence of lone pairs.
Inert pair effect also affects the properties of the p-Block elements especially for those elements which are present from 4th period onward and this happens due to poor screening effect of inner (n–1)d subshell electrons.
N2 is a gas whereas P4 is a solid, because -
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Nitrogen can form \(p\pi \) - \(p\pi \) bond while phosphorus cannot do so.
Because of its small size, nitrogen forms strong pπ–pπ multiple bonds with itself. It therefore exists as discrete N≡N diatomic molecules; only weak van der Waals forces act between these small molecules, so nitrogen is a gas. The larger phosphorus atom cannot form effective pπ–pπ bonds; it uses single P–P bonds and forms bigger P4 tetrahedra (and polymeric red and black phosphorus), so phosphorus is a solid.
Why the other options are incorrect
Option (1) Nitrogen is having higher electronegativity than phosphorus — Incorrect. The higher electronegativity of nitrogen is true, but it does not decide whether the element is made of small diatomic molecules or of larger \( \ce{P4} \) units.
Option (3) Atomic size of nitrogen is smaller than phosphorus — Incorrect. The small size of nitrogen is true, but it matters only because it allows pπ–pπ bonding; size alone does not explain the gaseous state.
Option (4) N2 is a non-polar molecular species whereas phosphorus in solid state forms polar bonds — Incorrect. The P–P bonds in solid phosphorus join identical atoms and are non-polar, so the statement is wrong.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Anomalous Properties of Nitrogen
