MolSynapsequestion bank
MolSynapse / Question bank / General Organic Chemistry I: Electronic Effects / Mesomeric effect and steric inhibition of resonance
JEE Main levelSingle correct optionDifficulty 2 of 3g1079

Arrange in decreasing order of acidity: (I) 4-nitrophenol, (II) 3-nitrophenol, (III) phenol.

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

Answer: B

In the 4-nitrophenoxide ion the negative charge is delocalised onto the nitro group through -M and -I effects. At the meta position the nitro group acts only through -I because it cannot conjugate with the oxygen. Phenol has no nitro group. The pKa values are about 7.2, 8.4 and 10, so the order is I > II > III.
Practice General Organic Chemistry I: Electronic Effects More on Mesomeric effect and steric inhibition of resonance
Previous questionNext question

More questions on Mesomeric effect and steric inhibition of resonance