Answer
A. no effect
B. no effect
C. left
D. right
Work Step by Step
Adding a gaseous reagent in an equilibrium reaction will always push the reaction towards the side that the reagent is not added to. Inversely, removing reagent will achieve the opposite result. Le Chatelier's principle describes this tendency of a reaction to recover to equilibrium after a disturbance. A and B have no effect because the reagents are solid.
