Which statement correctly describes a chemical equilibrium? it must take place in an open system the mass of the reactants and the mass of the products are no equal it is affected by the addition of a catalyst it does not involve a reversible reaction the concentrations of reactants and products are equal

In your choices, the best answer is the mass of the reactants and the mass of the products are no equal. The chemical equilibrium can take place in a close system and can not be affected by catalyst and is a reversible reaction. The best describe should be the concentration of reactants and products are constant.