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JEE Main levelSingle correct optionDifficulty 2 of 3g1083

Arrange in decreasing order of basicity in water: (I) 4-methylaniline, (II) aniline, (III) 4-nitroaniline.

  1. A
  2. B
  3. C
  4. D

Answer: B

The +I and hyperconjugation effects of the para methyl group increase electron density on nitrogen. The para nitro group withdraws electron density from the amino group by -M and -I, which lowers the availability of the lone pair. The pKa values of the conjugate acids are about 5.1, 4.6 and 1.0, so I > II > III.
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