Final answer:
The statement is false; the system at equilibrium does not need to consume all of the newly-added reactant or product to re-achieve equilibrium. The system will adjust and create a new equilibrium state without necessarily using up all of the added substance.
Step-by-step explanation:
When considering a chemical system at equilibrium, if a reactant or product is added, the equilibrium is disturbed. However, the system does not necessarily have to consume all of the newly-added amount to re-attain equilibrium; rather, it will shift in the direction that tends to counteract the change, according to Le Chatelier's Principle.
The system will change the rates of the forward and reverse reactions to establish a new equilibrium where the concentration of reactants and products will again become constant, but not necessarily identical to the original state before the addition.
It's essential to note that the system must be closed, no additional reactants can be added or products removed once equilibrium is established. This is what distinguishes it from a steady state system, which is not in chemical equilibrium due to the continuous flow of reactants in and products out.