1) increase in temperature (heat up). Since the reaction is exothermic because the ΔH value is negative, it means the heat is on the right side of the reaction, in the products; if there is an increase in temperature, the reaction shift away from the heat; to the left.
2) adding any of the product to the reaction, AB or C2 will cause the reaction to shift to the left because if we increase the concentrations of any, the reaction will try to decrease them by shifting away from them and use them as reactants.
3) you could increase the pressure. when pressure increases, the reaction shift to the side with less pressure, or fewer gas moles. this reaction has zero gas moles in the left but 1 in the right. so it shifts left. One way to increase the pressure is to decrease the volume of the container.
