Question

The $C-C$ bond length is $1.54$ $A^o$, $C$=$C$ bond length is 1.33 $A^o$. What is the circumference of benzene ring?

• A. $(3\times 1.54+3\times 1.33)A^o$
• B. $(4\times 1.54+21.33)A^o$
• C. $(6\times 1.4)A^o$ ($1.4$ is bond length between single and double bonds)
• D. $(4\times 1.33+2\times 1.54)A^o$

Answer 1

The correct option is C $(6\times 1.4)A^o$ ($1.4$ is bond length between single and double bonds)

In benzene due to resonance $C-C$ bond length is in between double bond and single bond.

i.e., $\frac{(1.54+1.33)}{2}=\frac{2.87}{2}=1.4$ $A^o$.

Hence circumference is $6\times C-C$ bond length (1.4).