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JEE Main levelSingle correct optionDifficulty 2 of 3g1238

The compound shown is cyclopropene. Which of the planar species shown, derived from a three-membered ring, is aromatic?

  1. AStructure A
  2. BStructure B
  3. CStructure C
  4. DStructure D

Answer: A

The cyclopropenyl cation has 2 pi electrons (4n+2, n = 0) in a planar ring, so it is aromatic. The anion has 4 pi electrons (antiaromatic), the radical has 3 pi electrons (neither closed-shell aromatic), and the saturated cyclopropyl cation has no pi system.
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