Question

Which allotrope of phosphorus is the most reactive?

(a) White phosphorus

(b) Metal phosphorus

(c) Red phosphorus

(d) Beta-black phosphorus

This question was posed to me during an interview.

This intriguing question comes from P-Block Elements topic in chapter P-Block Elements of Chemistry – Class 12

Answer 1

Correct option is (a) White phosphorus

Explanation: The three allotropic forms of phosphorus differ widely in their chemical reactivity in which white phosphorus is the most reactive while black and red phosphorus are less reactive. White phosphorus is made up of discrete P4 tetrahedra which are subjected to very high angular strain as the angles is 60 degrees. This high angular strain makes white phosphorus unstable and highly reactive.