Question

what is sigma bond . pls explain

Answer 1

In chemistry, sigma bonds (σ bonds) are the strongest type of covalent chemical bond. They are formed by head-on overlapping between atomic orbitals. Sigma bonding is most simply defined for diatomic molecules using the language and tools of symmetry groups.

Answer 2

Sigma bonds are the strongest bond between any diatomic molecule. It is also known as single bond. It forms Because of head-on overlapping between S-S, P-P, S-P orbitals.
Atom having Sigma bonds can rotate themselves to attain stability.