Answer:
Due to molecular structures.
Explanation:
The different forms of phosphorus (white, black or red) are allotropes of phosphorus.
They differ in molecular structures.
White phosphorus: It has four phosphorus which form a tetrahedral shape.
Black phosphorus : It has orthorhombic structure and due to interlinked six membered rings, it is least reactive.
Red phosphorus: It is formed on heating white phosphorus. It is initially amorphus and turns crystalline on further heating.
