Q1: If a two phase system is in physical equilibrium; then it means that, the

ANS:D - all (a), (b) and (c).

If a two-phase system is in physical equilibrium, it means that all of the given statements are true: a) The escaping tendency of each component from the liquid phase to the vapor phase is exactly equal to that from the vapor phase to the liquid phase. This indicates that there is no net transfer of molecules between the liquid and vapor phases, ensuring equilibrium. b) The temperature of the liquid phase is equal to that of the vapor phase. This condition ensures thermal equilibrium between the two phases. c) The total pressure throughout the liquid phase is equal to that throughout the vapor phase. This condition ensures that there is no pressure gradient between the two phases, indicating pressure equilibrium. When a two-phase system is in physical equilibrium, it implies that the system has reached a stable state where various properties are balanced between the liquid and vapor phases. Let's delve into each statement: a) The escaping tendency of each component from the liquid phase to the vapor phase is exactly equal to that from the vapor phase to the liquid phase: This statement refers to the dynamic equilibrium established between the liquid and vapor phases. Molecules are constantly moving between these phases, with some molecules escaping from the liquid into the vapor phase (evaporation) and others condensing from the vapor phase back into the liquid phase. In physical equilibrium, the rates of evaporation and condensation are equal, meaning there is no net transfer of molecules between the phases. This condition ensures that the system remains in equilibrium. b) The temperature of the liquid phase is equal to that of the vapor phase: In physical equilibrium, the system has reached thermal equilibrium, meaning that both phases are at the same temperature. This condition ensures that there is no net heat transfer between the phases, and they have the same average kinetic energy of molecules. c) The total pressure throughout the liquid phase is equal to that throughout the vapor phase: This statement reflects the condition of pressure equilibrium between the two phases. In physical equilibrium, the pressure exerted by the vapor phase (due to the vapor molecules) is equal to the pressure exerted by the liquid phase (due to the liquid molecules and any vapor present above the liquid). This equilibrium pressure ensures that there is no pressure gradient between the phases, preventing any further net vaporization or condensation. Therefore, when a two-phase system is in physical equilibrium, all of these conditions (a), (b), and (c) are met simultaneously, ensuring that the system remains stable and balanced. So, the correct answer is: d) all (a), (b), and (c).