The correct option is D A-p,r,s;
It is just a phase transition (sublimation) as no chemical change has occurred. Sublimation is always endothermic. Product is gas, more disordered. hence △ S is positive
It is a chemical decomposition, not a phase change. Thermal decomposition occur at the expense of energy, hence endothermic. Product contain a gaseous species, hence, △ S > 0.
A new H-H covalent bond is being formed, hence, △ H < 0. Also, product is less disordered than reactant, △ S < 0.
(D) Allotropes are considered as different phase, hence Pwhite,solid)→Pred,solid is a phase transition as well as allotropic change.
Also, red phosphorus is more ordered than white phosphorus, △ S < 0.