Ans- Sigma(σ) bond: Sigma bond is also termed as head-on overlap or axial overlap.

This type of covalent bond is formed when the overlapping is done from end to end along the internuclear axis. This may include the overlapping as follows:

• s-s overlapping

• s-p overlapping

• p–p overlapping

pi(π ) bond: The type of overlapping can be seen in a covalent bond that is formed when the bonding orbitals overlap sidewise, such that their axes are parallel to each other but perpendicular to the internuclear axis.