Assuming you start with equal concentrations of PCl3 and Cl2, and no PCl5 is initially present, describe the relative abundance of each species present at equilibrium.
a) [PCl3] decreases, [Cl2] decreases, [PCl5] increases
b) [PCl3] decreases, [Cl2] decreases, [PCl5] decreases
c) [PCl3] decreases, [Cl2] decreases, [PCl5] remains constant
d) [PCl3] remains constant, [Cl2] remains constant, [PCl5] increases