Question

Give reasons for the following:
(a) Red phosphorus is less reactive than white phosphorus.
(b) Electron gain enthalpies of halogens are largely negative.
(c) $N_2{O}_5$ is more acidic than $N_2{O}_3$

Answer 1

(a) White phosphorus is a molecular species, whereas its red phosphorus allotrope is non-molecular. And white phosphorus is encountered as the $P_4-P_4$ molecule, i.e. as a tetrahedron, and the associated ${60.0}^{\circ }$ angles introduce some degree of ring strain within the molecule.
(b) Because halogens have high effective nuclear charge.
(c) Because Nitrogen in $N_2{O}_5$ has higher oxidation state than $N_2{O}_3.$