Question is based on following passage:
Methyl nitrile is hydrolysed to carboxylic acid in the presence of \(H^+\) or \(OH^-\) as catalyst. An intermediate compound [A] is formed during this reaction.
Which of the following is the correct statement for hybridization of \(C-atom\) and number of \(\sigma \) and \(\pi \) bonds in the carbonyl group?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → sp2, 3σ, 1π
The carbonyl carbon is sp2-hybridised and forms three σ bonds (to O and to two other atoms) lying in one plane at about 120°. Its fourth electron, in the unhybridised p orbital, overlaps with a p orbital of oxygen to form one π bond. So C=O is one σ + one π bond, and the carbon has 3 σ and 1 π bond in all.
Why the other options are incorrect
Option (2) sp, 3σ, 1π — Incorrect. An sp carbon forms only two σ bonds (linear, 180°); the carbonyl carbon is trigonal.
Option (3) sp3, 3σ, 1π — Incorrect. An sp3 carbon forms four σ bonds and has no p orbital left for a π bond.
Option (4) sp3, 2σ, 2π — Incorrect. A carbon with two π bonds would be sp-hybridised, and the carbonyl carbon has only one double bond.
NCERT (2026-27 edition):
Structure of the Carbonyl Group
