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JEE Main · 2026 · 21 Jan 2026 · Shift 1 · General Organic Chemistry

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From the following, the least stable structure is:
  1. (A)(see structure)
  2. (B)(see structure)
  3. (C)(see structure)
    ✓ Correct
  4. (D)(see structure)

Answer: (C)

Solution

A contributing resonance structure is destabilised most when like charges sit on adjacent atoms. Among the charge-separated forms of the nitro-substituted butenyl system, three keep unlike charges adjacent or spread the charges apart, but one places a positively charged carbon directly bonded to the positively charged nitrogen of the nitro group. This neighbouring pair of positive charges creates strong electrostatic repulsion, so this form contributes least and is the least stable of the set.

JEE Main · 2026 · 21 Jan 2026 · Shift 1 · Single correct option

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