Question

Which of the following statement is correct?
(A) Hybrid orbitals do not form $\sigma $ bonds
(B) Lateral overlap of p-orbitals or p- and d- orbitals produce $\pi $ bonds.
(C) The strength of bonds follow the order: ${{\sigma }_{p-p}}<{{\sigma }_{s-s}}<{{\pi }_{p-p}}$
(D) s-orbitals do not form $\sigma $ bonds.

Answer 1

Hint: $\sigma $ bonds are formed by axial overlaps and $\pi $ bonds are formed by lateral overlap. Bonds with more energy are of lower strength, and bonds with more strength are lower in energy and are more stable.

Complete step by step answer: Chemical bonds are formed by either sharing of electrons known as covalent bonds or by donating or accepting electrons known as ionic bonds. In this question we will consider each statement one by one and analyse which statement is correct.
Considering statement (A), Hybrid orbitals are formed by mixing of orbitals. Hybridization of orbitals is greatly favored because hybridized orbitals are lower in energy compared to their separated, unhybridized counterparts. Hybrid orbitals do form $\sigma $ bonds.
Considering statement (B), Lateral overlap of p-orbitals and d-prbitals produce $\pi $ bonds. However, axial overlap of s- orbital and p-orbital forms $\sigma $ bonds.
Considering statement (C), The strength of bonds follow the order: ${{\sigma }_{p-p}}<{{\sigma }_{s-s}}<{{\pi }_{p-p}}$. This order is wrong. $\sigma $ bonds are formed by axial overlap and they are stronger than $\pi $ orbitals which are formed by lateral overlap. Therefore the strength of $\sigma $ bonds will be greater than $\pi $ bonds. Therefore, The strength of bonds follow the order:${{\sigma }_{p-p}}>{{\sigma }_{s-s}}>{{\pi }_{p-p}}$.
Considering statement (D), s-orbitals do not form $\sigma $ bonds. This statement is also wrong, as s-orbitals do form $\sigma $ bonds. S-orbital do not form $\pi $ bonds. As $\pi $ bonds are formed by axial overlap, and s-orbitals do not show axial overlap.


Note: Hybridisation was introduced to explain molecular structure when valence bond theory failed to correctly predict them. According to, VSEPR theory, electron pairs repel each other and the bonds and lone pairs around a central atom are generally separated by the largest possible angles.