Phosphorus Trichloride and Phosphorus Pentachloride Equilibrate in the Presence of Molecular

Phosphorus trichloride and phosphorus pentachloride equilibrate in the presence of molecular chlorine according to the following reaction: $\mathrm { PCl } _ { 3 }$ (g) + $\mathrm { Cl } _ { 2 }$ (g) ? $\mathrm { PCl } _ { 5 }$ (g) An equilibrium mixture at 450 K contains $\mathrm { P } _ { \mathrm { PCl } _ { 3 } }$ = 0.124 bar, $\mathrm { P } _ { \mathrm { Cl } _ { 2 } }$ = 0.157 bar,and $\mathrm { P } _ { \mathrm { PCl } _ { 5 } }$ = 1.30 bar.What is the value of K_p at this temperature?

A) 66.8 bar^-1
B) 4.63 bar^-1
C) 2.53 × 10^-2 bar^-1
D) 1.50 × 10^-2 bar^-1
E) 1.03 bar^-1