This is an incomplete question, here is a complete question.
Ammonia is produced commercially by the Haber reaction:
The formation of ammonia is favored by
A) an increase in pressure
B) a decrease in pressure
C) removal of N₂(g)
D) removal of H₂(g)
Answer : The correct option is, (A) an increase in pressure.
Explanation :
Any change in the equilibrium is studied on the basis of Le-Chatelier's principle.
Le-Chatelier's principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.
Increase the pressure :
If the pressure in the equilibrium is increased, the equilibrium will shift in the direction where fewer total molecules are shown in the balanced chemical equation.
In the given reaction, there are 4 molecules present on reactant side and 2 molecules on product side. That means, less molecules present on product side. Thus, the reaction will shift in right direction that is towards the product.
Removal the reactant molecule :
If any of reactant molecule in the equilibrium is removed, then the equilibrium will shift in left direction that is towards the reactant.
Hnece, the formation of ammonia is favored by an increase in pressure.