The production of ammonia (nh3) is exothermic and is in equilibrium with its breakdown (which is endothermic):
n₂ + 3h₂ ⇋ 2nh₃
if the concentration of h2 is decreased, will the equilibrium shift to produce more or less ammonia? justify your answer.

The equilibrium will shift to produce less ammonia

Explanation:

According to Le Chatelier's principle, the reaction will try to oppose anything that is done on it, if it was at equilibrium.

When the concentration of H2 is decreased, you are decreasing the concentration of hydrogen so the reaction tries to increase the concentration of hydrogen by breaking down the ammonia on the products side. This will decrease the output of ammonia