The following two reactions:
i. `PCl_(5)(g) hArr PCl_(3)(g)+Cl_(2)(g)`
(ii) `COCl_(2)(g) hArr CO(g)+Cl_(2)(g)`
are simultaneously in equilibrium in a container at constant volume. A few moles of `CO(g)` are later introduced into the vessel. After some time, the new equilibrium concentration of
A. `PCl_(5)` increases
B. `PCl_(5)` remains unchanged
C. `PCl_(5)`decreases
D. `Cl_(2)` increase