Among the following, the molecule with s-s overlapping is

Solution:

In the given list ${\text{I}}_2$ ,$\text{C}{l}_2$  molecules are formed by p-p overlapping of p orbital of each atom and forms one $\sigma$   bond in${\text{I}}_2$ ,$\text{C}{l}_2$ molecules whereas HCl molecule is formed by end on end overlapping of s orbital of H atom and p orbital of Cl atom. The ${\text{H}}_2$ molecule is formed by end on end overlapping of s orbital of H atom and s orbital of another H atom.