Moderate

The C-N bond length in the molecules is most correctly in the order:

Correct answer: A. II > III > I > IV

  • A. II > III > I > IV
  • B. II > III = I > IV
  • C. III > IV > I > II
  • D. IV > III > IV > I

Explanation

As the s-character of the hybridized orbital of the C-atom increases, the bond length decreases. A double bond is shorter than a single bond. Participation of lone pair on N atom in resonance induces partial double-bond character between C and N.(II) has a single bond between C and N so it has the longest length. (III) has a single bond and N has no lone pairs. (I) has partial C and N double bonds. (IV) has double C and N bonds.

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