The number of unpaired electrons in a paramagnetic diatomic molecule of an element with atomic number 16 is :

The element with atomic number 16 is Sulfur. In the vapor phase, sulfur forms diatomic ${\text{S}}_2$ molecules which are analogous to ${\text{O}}_2$. Following Molecular Orbital Theory, the two highest energy electrons in ${\text{S}}_2$ occupy the degenerate anti-bonding ${\pi }^{\ast }$ orbitals (${\pi }_{3px}^{\ast }$ and ${\pi }_{3py}^{\ast }$) singly with parallel spins, making the molecule paramagnetic with 2 unpaired electrons.