Question

Why sigma bonds break easily than pie bond.

Answer 1

Pi bonds are easier to break than sigma bonds. The end-on overlap of orbitals to form a sigma bond is more efficient than the side-on overlap of orbitals to form a pi bond. The electrons in a sigma bond are directly between the two nuclei. They are as close to the nuclei as they can get.

Answer 2

Because of low intermolecular bonding less than the pi bond.