Given the diagram representing a closed system at constant temperature: Which statement describes this system at equilibrium? 1. The mass of H 2 O( ) equals the mass of H 2 O (g). 2. The volume of H 2 O ( ) equals the volume of H 2 O (g). 3. The number of moles of H2 O ( ) equals the number of moles of H2 O (g). 4. The rate of evaporation of H2 O ( ) equals the rate of condensation of H2 O (g).