Final answer:
The carbon-carbon bond length in benzene is 140 pm, which is intermediate between the typical single and double bond lengths, due to the delocalization of electrons across the aromatic ring.
option c is the correct
Step-by-step explanation:
When considering the bond lengths in a benzene molecule, it's important to understand that benzene displays resonance, meaning that the double and single bonds depicted in its different resonance forms do not truly represent the actual structure of the molecule.
In reality, the electrons that form these bonds are delocalized over the entire ring, creating a bond length that is intermediate between that of a typical carbon-carbon single bond and a double bond.
The length of a single carbon-carbon bond is 154 pm and that of a double bond is 133 pm, but in benzene, where the bonding situation is an average of these two extremes, the bond length is found to be 139.9 pm. This intermediate bond length is a result of the delocalized pi electrons in the aromatic ring. The correct expected length for the carbon-carbon bonds in benzene would therefore be 140 pm.