Which of the following compounds do not have all C-C bond of same length?

Options

A.
B.
C.
D.

Answer

To determine which of the given compounds do not have all C-C bonds of the same length, we need to analyze the resonance structures and bond characteristics of each compound.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have four compounds labeled A, B, C, and D. We need to analyze each compound to see if all C-C bonds are of the same length.

2. **Analyze Compound A**:
- Draw the resonance structures for compound A (which is naphthalene).
- Naphthalene has alternating double bonds, and when you draw its resonance structures, you will find that the bonds between certain carbon atoms (like between 8-9 and 7-6) have more double bond character than others (like between 10-5).
- This indicates that the bond lengths are not the same due to varying double bond character.

3. **Analyze Compound B**:
- For compound B, draw its resonance structures.
- In this compound, the double bond character is consistent across the structure, meaning that all C-C bonds have the same length.

4. **Analyze Compound C**:
- Draw the resonance structures for compound C.
- Similar to compound B, all C-C bonds in this compound exhibit the same double bond character, leading to equal bond lengths.

5. **Analyze Compound D**:
- Draw the resonance structures for compound D (which is benzene).
- Benzene also has equal bond character across all C-C bonds due to resonance, resulting in all bonds being of the same length.

6. **Conclusion**:
- From the analysis, we find that only compound A (naphthalene) has C-C bonds of different lengths due to the varying double bond character in its structure.
- Therefore, the compound that does not have all C-C bonds of the same length is **A**.

### Final Answer:
The compound that does not have all C-C bonds of the same length is **A** (Naphthalene).