`-oversetoverset(O)(||)C-ddotNH`-(peptide bond ) which statement is incorrect about peptide bond : -

Options

A. C–N bond length in protiens is longer than usual bond length of N-bond
B. Spectroscopic analysis show planar structure of `-undersetunderset(O)(||)C-NH-` group
C. C–N bond length in proteins is smaller than usual bond length of C–N bond
D. None of above

Answer

To determine which statement is incorrect about the peptide bond, we need to analyze the given statements regarding the characteristics of the peptide bond, particularly focusing on the C-N bond length and its properties.

### Step-by-Step Solution:

1. **Understanding the Peptide Bond Structure**:
- A peptide bond is formed between the carboxyl group of one amino acid and the amino group of another, resulting in a structure represented as C(=O)-N-H.

2. **Analyzing Statement A**:
- Statement A claims that the C-N bond length in proteins is larger than the usual bond length of the C-N bond.
- In reality, the C-N bond in a peptide bond has some double bond character due to resonance, which typically makes it shorter than a standard C-N single bond. Therefore, this statement is **incorrect**.

3. **Analyzing Statement B**:
- Statement B states that spectroscopic analysis shows a planar structure of the C(=O)-N-H group.
- This is a correct statement because the peptide bond is indeed planar due to the partial double bond character, which restricts rotation.

4. **Analyzing Statement C**:
- Statement C claims that the C-N bond length in proteins is smaller than the usual bond length of C-N.
- This statement is correct as the resonance in the peptide bond gives it a shorter bond length compared to a typical C-N single bond.

5. **Analyzing Statement D**:
- Statement D states "none of the above," which cannot be correct since we have identified Statement A as incorrect.

### Conclusion:
The incorrect statement about the peptide bond is **Statement A**: "C-N bond length in proteins is larger than usual bond length of C-N."