Question

Pick out the odd property of rhombic Sulphur:
A. Rhombic Sulphur exists as octahedral crystals.
B. The density of rhombic Sulphur is $2.06\text{ }g/mL.$
C. Rhombic Sulphur is yellow solid with a melting point $385.8K$ and is soluble in carbon disulphide and insoluble in water.
D. None of the above.

Answer 1

We know that the two important allotropes of the homocyclic category are yellow rhombic and monoclinic Sulphur. Rhombic Sulphur is also known as α Sulphur whereas monoclinic Sulphur is known as β Sulphur. Sulphur has more allotropic forms than any other element.

Complete answer:
As we know, the rhombic Sulphur occurs naturally as large yellow crystals in volcanic areas. It has a melting point $385.8\text{ }K$ and specific gravity $2.06$ and rhombic Sulphur crystals are formed on evaporating the solution of roll Sulphur in $C{{S}_{2}}.$ These two forms are interconvertible and at the temperature above $369K$ rhombic Sulphur gets converted to monoclinic and at the temp below $369K$ monoclinic Sulphur changes to rhombic. Also, the temperature of $369K$ both forms of Sulphur exists and this temperature is called the transition temperature. Rhombic Sulphur or orthorhombic Sulphur is a molecular solid which consists of a puckered ring having a crown shape. It is also known as octahedral Sulphur. Rhombic Sulphur is the most stable form of Sulphur at room temperature and is prepared by slow evaporation of a solution of roll Sulphur in carbon disulphide in the China dish. As a result, the octahedral crystal of rhombic Sulphur appears. Rhombic Sulphur has very small thermal and electrical conductivity and its melting point is $385.8\text{ }K$.

So, the correct answer is “Option D”.

Note:
Remember that the rhombic Sulphur is insoluble in water but dissolves to some extent in benzene, alcohol, and ether and is easily soluble in carbon disulphide. When it dissolves in a boiling concentrated solution of sodium sulphite it forms sodium thiosulphate.