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NEET levelSingle correct optionDifficulty 1 of 3g2059

In pyridine the lone pair on nitrogen is available for protonation because it

  1. Ais part of the six pi electrons of the aromatic ring
  2. Blies in an sp orbital in the plane of the ring and is not part of the aromatic sextet
  3. Cis delocalised over all five carbon atoms
  4. Dis absent, since nitrogen forms three sigma bonds

Answer: B

Each ring atom of pyridine contributes one p electron to the aromatic sextet. The N lone pair sits in an sp orbital in the ring plane, perpendicular to the pi cloud, so it can accept to give the pyridin-1-ium ion with aromaticity intact.
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