What will the system do if pressure is increased in a reaction at equilibrium?

When the pressure in a reaction at equilibrium is increased, the system responds according to Le Chatelier's principle. This principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change.

In the case of increased pressure, the equilibrium will shift towards the side of the reaction that has fewer moles of gas. This is because, in order to reduce the pressure, the system favors the formation of products or reactants that occupy less volume. If one side contains more gas molecules than the other, shifting to the side with fewer gas molecules decreases the total number of particles in the gaseous state and thus lowers the pressure.

Consequently, the correct response accurately reflects the behavior of the equilibrium system in reaction to pressure changes, demonstrating an understanding of how gaseous equilibria adjust to maintain balance in response to external factors.