We have that the reaction and a decrease in the concentration of the reactants will favor the reverse reaction that is the decomposition of the yellow iodine trichloride and the formation of green chlorine gas and brown iodine chloride
Given that some green chlorine gas, which is part of the reactant, will be removed, the reverse reaction will be favored and initial concentration of the yellow iodine trichloride and the green chlorine gas will be reduced while the proportional concentration of the brown iodine chloride will increase and the mixture will become more brown.
