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JEE Advanced levelSingle correct optionDifficulty 3 of 3g1160

Assertion (A): Pyrrole is a much weaker base than pyridine. Reason (R): In pyrrole the lone pair on nitrogen is part of the aromatic sextet, whereas in pyridine the lone pair lies in the plane of the ring outside the sextet.

  1. ABoth Assertion and Reason are true and Reason is the correct explanation of Assertion
  2. BBoth Assertion and Reason are true but Reason is not the correct explanation of Assertion
  3. CAssertion is true but Reason is false
  4. DAssertion is false but Reason is true

Answer: A

Protonation of pyrrole at nitrogen would use the lone pair that completes the 6 pi electron sextet, destroying aromaticity. Pyridine's lone pair is in an sp2 orbital outside the pi system and is available. The Reason correctly explains the Assertion.
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