P Block Elements – JEE Main ChemistryPractice Questions & PYQs

Phosphorus exhibits various allotropic forms that are fundamentally determined by the specific conditions under which they are synthesized. The starting material $A$, which is white phosphorus, is converted into red phosphorus when heated to 573 K in an inert atmosphere. Upon heating this red phosphorus in a sealed tube at 803 K, it undergoes a transformation to yield the final product $B$, which is $\alpha$-black phosphorus. Thus, the sequence identifies the initial substance as white phosphorus and the final result as $\alpha$-black phosphorus.