Question

The ratio of sigma and pi bonds in benzene is:
A.3:1
B.4:1
C.2:1
D.1:1

Answer 1

Hint: Sigma Bonds are the bonds formed due to the head on overlap of the orbitals while the pi bonds are formed by the sidewise overlap of the orbitals. A double bond contains one sigma and one pi bond.

Complete Step by step solution:
In the benzene molecule the carbon atoms are $\text{s}{{\text{p}}^{\text{2}}}$ hybridized and hence they have one ‘p’ orbital that does not participate in the hybridization and the lone electron in that p-orbital overlaps sideways with the other p-orbitals on the side and hence they form a pi-bond due to the sidewise overlap of the orbitals. The p-orbitals being axial, the overlap takes place sidewise and hence the pi-bond is formed. As there are six different p-orbitals, so the electrons are delocalized over the entire molecule. And appear as an electron cloud. Hence there are six sigma bonds between the six carbon atoms due to the overlap of the head-on overlap of the orbitals and three pi-bonds due to the side-wise overlap of the orbitals.
So, the ratio of the sigma to the pi bonds is 2:1,

so, the correct option is C.

Notes: As the sigma bonds are formed due to the head-on overlap of the orbitals, so they are stronger in comparison to the pi-orbitals that are formed from the sidewise overlap of the orbitals. Due to the delocalization of the electrons in the six p-orbitals of the benzene molecules have canonical or resonating structures which provide extra stability to the molecules.