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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3nm025

Which of the following statements is/are correct?

  1. APyridine is a heterocyclic aromatic compound with a degree of unsaturation of 5.
  2. BTetrahydrofuran is a saturated heterocyclic compound with a degree of unsaturation of 1.
  3. CCyclohexene is an unsaturated alicyclic compound with a degree of unsaturation of 2.
  4. DFuran is a heterocyclic aromatic compound with a degree of unsaturation of 3.

Answer: B, C, D

Furan is C4H4O: DU = (8 + 2 - 4)/2 = 3 (one ring and two C=C), and it is a heterocyclic aromatic compound. Pyridine is C5H5N: DU = (10 + 2 + 1 - 5)/2 = 4, not 5. Tetrahydrofuran is C4H8O with DU 1 from the ring alone, so it is saturated. Cyclohexene is C6H10 with DU 2 (ring plus C=C) and is alicyclic.
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