Question

Plastic sulphur is _ of ${{S}_{8}}$ molecule.
A.An open chain
B.Closed chain
C.Branch chain
D.None of these

Answer 1

Sulphur has many allotropes, plastic sulphur is one of them. This kind of sulphur is made by supercooling liquid sulphur and it forms a metastable structure. These properties are different from other allotropes of sulphur which have a close chained structure.

Complete answer:
The correct answer to this question is option A, plastic sulphur has an open chain structure. This open chain structure is made of ${{S}_{8}}$ molecules.
Plastic sulphur is just another allotrope of sulphur made from liquid sulphur. It is obtained by supercooling or rapid cooling of liquid sulphur or molten sulphur. At room temperature, it takes a helical form and has a metastable state, also it resembles properties and visuals like unvulcanised rubber. It is red and is a rubber-like substance.
Plastic sulphur is also known as amorphous sulphur because it has long chains of sulphur atoms. There is also another allotrope of sulphur with ${{S}_{8}}$ composition and has the shape of a crown. It is known as octasulfur, it is tasteless colourless and is a yellow solid substance.
The chains that are formed in plastic sulphur are held by Van Der Waals forces, thus as the forces are weak, plastic sulphur is unstable at room temperature. Thus the chain is unstable and can go back to original form.

Note:
As plastic sulphur is unstable at room temperature, it slowly goes back to crown shaped ${{S}_{8}}$ structure. As it goes back to rubber-like crown shaped molecular structure, it becomes brittle. Brittleness of the structure comes from the crystals that are formed.