Answer:
Choice d. No effect will be observed as long as other factors (temperature, in particular) are unchanged.
Explanation:
The equilibrium constant of a reaction does not depend on the pressure. For this particular reaction, the equilibrium quotient is:
.
Note that the two sides of this balanced equation contain an equal number of gaseous particles. Indeed, both and
will increase if the pressure is increased through compression. However, because
and
have the same coefficients in the equation, their concentrations are raised to the same power in the equilibrium quotient
.
As a result, the increase in pressure will have no impact on the value of . If the system was already at equilibrium, it will continue to be at an equilibrium even after the change to its pressure. Therefore, no overall effect on the equilibrium position should be visible.