Answer the question on basis of passage given below:
Nitrogen differs from the rest of the members of its group due to its small size, high electronegativity, high ionisation enthalpy and non-availability of d-orbitals. Nitrogen has unique ability to form \(p\pi-p\pi\) multiple bonds with itself and with other elements having small size and high electronegativity (e.g., C, O). Heavier elements of this group do not form \(p\pi-p\pi\) bonds as their atomic orbitals are so large and diffused that they cannot have effective overlapping.
In the elemental state, a single bond is not formed between two atoms of:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \(N - N\)
Because of its small size and high electronegativity, nitrogen forms strong pπ–pπ multiple bonds with itself: elemental nitrogen is N≡N. The heavier members have large, diffuse orbitals that cannot form effective pπ–pπ overlap, so they join their atoms by single bonds.
Option (1) P – P — A single bond in the elemental state. White phosphorus is made of \( \ce{P4} \) tetrahedra held by P–P single bonds.
Option (2) N – N — No single bond in the elemental state. The two N atoms are joined by a triple bond (one σ, two π; 941.4 kJ mol−1). N–N single bonds occur only in compounds such as hydrazine.
Option (3) As – As — A single bond in the elemental state. Arsenic forms As–As single bonds (\( \ce{As4} \) in yellow arsenic, layers in grey arsenic).
Option (4) Sb – Sb — A single bond in the elemental state. Antimony likewise forms Sb–Sb single bonds.
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 – “… Heavier elements of this group do not form pπ–pπ bonds as their atomic orbitals are so large and diffuse that they cannot have effective overlapping. Thus, nitrogen exists as a diatomic molecule with a triple bond (one s and two p) between the two atoms. Consequently, its bond enthalpy (941.4 kJ mol−1) is very high. On the contrary, phosphorus, arsenic and antimony form single bonds as P–P, As–As and Sb–Sb while bismuth forms metallic bonds in elemental state.”