What does Le Châtelier's principle say about upsetting a system at equilibrium? A. A system will go to completion if equilibrium conditions are changed. B. A system will not be able to restore equilibrium if conditions are changed. C. A system whose equilibrium has been upset will shift to restore equilibrium. D. A system at equilibrium will stay at equilibrium even if conditions are upset.

C. A system whose equilibrium has been upset will shift to restore equilibrium. When an external change such as concentration, temperature, or pressure is applied to a system at equilibrium, Le Châtelier's principle suggests that the system will adjust itself in a way that counteracts the change. For example, if you increase the concentration of reactants, the system will favor the forward reaction to produce more products, effectively trying to restore that delicate balance of equilibrium. Isn't it fascinating how nature strives for balance? If you ever want to see Le Châtelier's principle in action, try adding vinegar to a solution of baking soda. The increased concentration of reactants causes a vigorous reaction that produces carbon dioxide gas, illustrating how an equilibrium shifts when conditions are altered. It’s a fun and fizzy way to see chemistry principles come alive right in your kitchen!