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Question 770011
JEE Chemistry · Hard

Hydrocarbons: JEE Advanced MCQ

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JEE AdvancedHardQuestion 770011

Question

Cyclopentadienyl anion (C₅H₅⁻) is aromatic because:
  1. A
    It has 6 π electrons satisfying Hückel's rule (4n+2, n=1)
    Correct
  2. B
    It has 5 π electrons
  3. C
    It has 4 π electrons
  4. D
    Cyclic conjugation alone makes it aromatic

Correct answer

It has 6 π electrons satisfying Hückel's rule (4n+2, n=1)

Explanation

C₅H₅⁻ has 5 carbons, 4 π electrons from double bonds + 1 lone pair from the carbanion = 6 π electrons total. Hückel's rule: 4n+2 = 6 (n=1). Cyclic, planar, fully conjugated + 6π electrons → aromatic.

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