All C-C bonds in benzene are of equal length.

Answer

To understand why all C-C bonds in benzene are of equal length, we can break down the explanation into several steps:

### Step 1: Structure of Benzene
Benzene is a cyclic hydrocarbon with the formula C₆H₆. It consists of six carbon atoms arranged in a hexagonal ring, with alternating single and double bonds.

### Step 2: Resonance in Benzene
In benzene, the actual structure is not a simple alternating single and double bond arrangement. Instead, benzene exhibits resonance. This means that the electrons in the double bonds are not localized between two specific carbon atoms; rather, they are delocalized across the entire ring.

### Step 3: Delocalization of Electrons
Due to this delocalization, the π (pi) electrons are spread out over all six carbon atoms. This creates a situation where all carbon-carbon bonds are equivalent, rather than having distinct single and double bonds.

### Step 4: Bond Length in Benzene
The bond length of the carbon-carbon bonds in benzene is measured to be approximately 1.39 Å. This bond length is intermediate between a typical carbon-carbon single bond (about 1.54 Å) and a carbon-carbon double bond (about 1.34 Å). This indicates that all bonds in benzene are of equal length due to the resonance effect.

### Step 5: Conclusion
In conclusion, the equality of the C-C bond lengths in benzene is a result of the resonance and delocalization of electrons, which leads to the formation of equivalent bonds throughout the structure.

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