Question

In benzene all $$C-C$$ bond length between all carbon atoms are equal because of:
A.Tautomerism
B.$$S{p}^2$$ hybridisation
C.Isomerism
D.Resonance

Answer 1

Hint: Benzene is an organic molecule. It is a resonance hybrid of various canonical structures. Resonance is the delocalization of electrons. Electron delocalization can stabilize benzene.
Complete step by step answer:
Benzene is an organic molecule having the molecular formula $$C_6{H}_6$$ . The structure of benzene is given below.

 All the carbon atoms are $$S{p}^2$$ hybridised. These $$S{p}^2$$ hybrid orbitals are arranged in a triangular planar fashion. One of the unhybridized p orbital will remain perpendicular to the above plane. Each C atom will use two of the $$S{p}^2$$ hybridized orbital and form 2 $$C-C$$ sigma bonds by $$s{p}^2-s{p}^2$$ head-on overlap. The remaining $$S{p}^2$$ orbital is used to form a sigma bond by overlap with the 1s orbital of hydrogen. There will be 6 $$C-C$$ sigma bonds that form the sides of the hexagon. All the $$C-C-C$$ bond angles will be $${120}^{\circ }$$ .
According to the resonance concept, benzene is a resonance hybrid of the following structures.

The resonance explains the unusual stability of benzene. The resonance hybrid will have a lower energy than the contributing structures. The resonance energy of benzene is -150.5 kJ/mol.
The six mutually parallel unhybridized p orbitals will stand perpendicular to the hexagonal carbon ring and overlap sideways above and below the plane of the ring. Due to the delocalization of pi electrons all the carbon-carbon bonds of benzene have the same length.

Note: All the six carbon-carbon bonds in benzene have equal length. It is greater than carbon-carbon double bond length and lower than carbon-carbon single bond length. Carbon-carbon bond length in benzene is 1.39 angstrom. In contrast to alkenes benzene undergo substitution reactions rather than additional reactions. There are two resonance structures for benzene; these are kekule and dewar structures. Kekule structure has some limitations. It could not explain the remarkable stability of benzene towards strong oxidants like $$KMn{O}_4$$ .