Consider the reaction described by the following equation. CO2 (g) + H2 (g) ⇌CO (g) + H2O (g) How will the position of the equilibrium change if the volume of a vessel that contains this reaction is decreased?

If volume is decreased equilibrium shifts to the side with fewest moles of gas therefore equilibrium shifts to the side with least moles. However as the number of moles of gas are equal on both sides in your equation the position of equilibrium does not change.