Which statement is incorrect about peptide bond?

• Correct answer
  A

  $\mathrm{C}-\mathrm{N}$ bond length in proteins is longer than usual $\mathrm{C}-\mathrm{N}$ bond length.
• B

  Spectroscopic analysis shows planar structure of
  bond.
• C

  $\mathrm{C}-\mathrm{N}$ bond length in proteins is smaller than usual $\mathrm{C}-\mathrm{N}$ bond length.
• D

  None of these

Solution

Due to resonance,
bond acquires some double bond character, hence shorter in length.

Hence, the correct answer is option: 'A'.