Why is sigma bond stonger than $\pi $-bond ? Explain



The strength of a bond depends upon the extent of overlapping. Since in the formation of a-bond, overlapping is along the internuclear axis, there-fore there is considerable overlapping. Hence, the a-bond is a strong bond. On the other hand, in case of the formation of a $\pi $-bond, sideways overlapping takes place which is only to a small extent. Hence, $\pi $-bond is a weak bond