A translucent white waxy solid (A) on heating in an inert atomosphere is converted to its allotropic form (B). The solid (A) on reaction with very dilute aqueous KOH liberates a highly poisonous gas (C ) having rotten fish smell. With excess of chlorine, (A) forms (D) which hydrolyses to compound (E ). Identify compounds (A) to (E ).

Explanation

(A) White waxy solid (A) is white phosphorus. When white phosphorus is heated in an inert atmosphere at 573K, it changes to red phosphorus.
(B) is red phosphorus.
(a) On heating with KOH liberates phosphine.
(c) Which is poisonous gas with rotten fish smell.
`{:(P_4+3KOH+3H_2OtoPH_3+3KH_2PO_2),(""" Phosphine(c)"):}`
White phosphorus (`P_4`) burns with excess of `Cl_2` to form phosphorus pentachloride (D).
`{:(P_4+10Cl_2overset("heat")to4PCl_5),(" "(D)):}`
Hydrolysis of (D) gives phosphoric acid (E)
`{:(PCl_5+4H_2OtoH_3PO_4+5HCl),(" "(E)):}`