The statement that is not true concerning equilibrium is: ‘The equilibrium constant usually is independent of temperature.’
Explanation: The equilibrium constant (K) is actually dependent on temperature. According to Le Chatelier’s principle, if the temperature of a system at equilibrium is changed, the system will adjust to counteract that change. This means that the equilibrium position will shift, and consequently, the value of the equilibrium constant will change. For example, in an exothermic reaction, increasing the temperature will shift the equilibrium to favor the reactants, thereby decreasing the value of K. Conversely, in an endothermic reaction, increasing the temperature will shift the equilibrium to favor the products, increasing the value of K.
On the other hand, the statement ‘Equilibrium in molecular systems is dynamic with two opposing processes balancing one another’ is true. At equilibrium, the forward and reverse reactions occur at the same rate, resulting in no net change in the concentrations of reactants and products over time.