Rhombic sulfur is the most allotropic form of sulfur.
A. True
B. False

Hint: Sulfur is a chemical element represented by the symbol S and has atomic number 16. It is generally a yellow crystalline solid and generally non-metal. It is insoluble in water and is a poor conductor of electricity.

Complete Solution :
- The term allotropes defined as the one or more physical forms of a chemical element that occurs in the same physical state. Allotropes may show differences in chemical and physical properties. Sulfur can be found in a number of structures in the same physical state. However, the most important crystalline structures are rhombic also known by the name octahedral and monoclinic sulfur. The two main allotropes of sulfur are rhombic and monoclinic sulfur.
- Rhombic sulfur can be defined as yellow and translucent crystals. It has a melting point of $114{}^\text{o}C$ and the density of rhombic sulfur is $2.08gc{{m}^{-3}}$ and it is stable at temperatures below $96{}^\text{o}C$.
- Monoclinic sulfur are transparent and amber crystals show a melting point of $119{}^\text{o}C$. The density of monoclinic sulfur is $1.98gc{{m}^{-3}}$ and it is unstable at temperatures below $96{}^\text{o}C$ and changes into rhombic form. At a temperature of $96{}^\text{o}C$ or above the rhombic sulfur changes to kaleidoscopic or prismatic sulfur and at $96{}^\text{o}C$ or below $96{}^\text{o}C$ kaleidoscopic or prismatic sulfur changes to rhombic sulfur.
- Out of these two allotropes of nature rhombic form is most stable so we can say that the given statement is true. So, the correct answer is “Option A”.

Note: Those allotropes that change their configuration from one form to another by a change in the temperature are known as enantiotropic allotropes. Other than rhombic or monoclinic there are also 2 other forms of sulfur known as colloidal sulfur and milk sulfur.