Q.Which form of sulfur shows paramagnetic behaviour ?

At elevated temperature sulfur vapour partly consists of the diatomic S$_2$ molecule, which -- exactly like O$_2$ of the same group -- carries two unpaired electrons. …

Step 1. Solid sulfur (rhombic or monoclinic S$_8$, cyclo-S$_6$, etc.) has all its electrons paired and is diamagnetic -- the magnetically distinctive form appears only in the vapour.

Step 2. In the vapour state (at elevated temperature, ~1000 K) sulfur partly exists as the diatomic molecule S$_2$. …

Recalling that the S2 molecule of sulfur vapour is the group-16 analogue of O2, then applying the same molecular-orbital argument (tw …

• Naming rhombic or monoclinic sulfur: both are S8 solids with every electron paired (diamagnetic).
• Saying 'sulfur vapour' without identifying the S2 species that actually carries the unpaired electrons. …