2.2 moles of phosphorus penta chloride were taken in a closed vessel and dissociated into phoshorus trichloride and chlorine. At equilibrium, the total number of moles of the reactants and the products was 2.53. The degree of dissociation is;

It is given to find the degree of dissociation.2.2 moles of phosphorus penta chloride were taken in a closed vessel and dissociated into phoshorus trichloride and chlorine. At equilibrium, the total number of moles of the reactants and the products was 2.53.

${\mathrm{PCl}}_5\rightleftharpoons {\mathrm{PCl}}_3+{\mathrm{Cl}}_2$

Initially Mole 2.2

After dissociate $2.2(1-\alpha ) 2.2\propto 2.2\propto$

$\text{Total moles }=2.2-2.2c+2.2\propto +2.2c$

=2.2(1+c)=2.53

Alpha=0.15 Ant 

Hence the correct option is (C) 0.15