The constant value of the reaction quotient shown by a system at equilibrium is called the:

1. The numerical value of the reaction quotient varies as a reaction proceeds towards equilibrium. 2. Once equilibrium is reached it stops changing. 3. The constant value of the reaction quotient exhibited by a system at equilibrium is called the equilibrium constant, K. 4. A rate constant belongs to kinetics rather than to equilibrium. _Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 13 'Fundamental Equilibrium Concepts', sections 13.1-13.4_