JEE Main 2025 Jan 24 Shift 2, Chemistry Q5: Valence Bond Theory And Hybridisation

Hybridisation is assigned from the number of $\sigma$-bonds plus lone pairs (steric number) at each carbon:

• Carbonyl C (C=O): one $\pi$ bond $\Rightarrow$ $s{p}^2$
• Two C atoms of the first C=C: both $s{p}^2$
• Two C atoms of the C≡C triple bond: both $sp$
• Two C atoms of the second C=C: both $s{p}^2$
• Nitrile carbon (-C≡N): $sp$

Tally: $sp$ carbons $=2+1=3$;   $s{p}^2$ carbons $=1+2+2=5$.

Correct option: (2)