Arrange in decreasing order of electron density in the benzene ring: (I) C6H5-NH2, (II) C6H5-OCH3, (III) C6H5-Cl, (IV) C6H5-NO2.

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Arrange in decreasing order of electron density in the benzene ring: (I) $C X_{6} H X_{5} - NH X_{2}$ , (II) $C X_{6} H X_{5} - OCH X_{3}$ , (III) $C X_{6} H X_{5} - Cl$ , (IV) $C X_{6} H X_{5} - NO X_{2}$ .

A $IV > III > II > I$
B $I > II > III > IV$
C $I > II > IV > III$
D $II > I > III > IV$

Answer: B

The

- NH X_{2}

group has the strongest +M effect (nitrogen is less electronegative than oxygen), followed by

- OCH X_{3}

. Chlorine has +M weaker than its -I, so the ring is somewhat poorer in electrons than benzene. The nitro group withdraws strongly by -M and -I. The order is I > II > III > IV.

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Arrange in decreasing order of electron density in the benzene ring: (I) CX6​HX5​−NHX2​, (II) CX6​HX5​−OCHX3​, (III) CX6​HX5​−Cl, (IV) CX6​HX5​−NOX2​.

Answer: B

More questions on Mesomeric effect and steric inhibition of resonance

Arrange in decreasing order of electron density in the benzene ring: (I) $C X_{6} H X_{5} - NH X_{2}$ , (II) $C X_{6} H X_{5} - OCH X_{3}$ , (III) $C X_{6} H X_{5} - Cl$ , (IV) $C X_{6} H X_{5} - NO X_{2}$ .