α−sulphur⇌<369K>369Kβ−sulphur
at room temperature α-sulphur (Rhombic) is most stable form.
The most stable allotropic form of sulphur is Rhombic sulphur.
Since both rhombic and monoclinic are nonpolar in nature so, they are soluble in non-polar solvents like carbon disulphide (CS2​).
Both rhombic and monoclinic sulphur has the molecular formula S8.​