Quality of 100% corresponds to which state?

• A. Saturated or dry, steam
• B. Superheated steam
• C. Liquid water
• D. Two-phase mixture

Answer: (A)

Quality is the fraction of mass that is vapor in a saturated liquid–vapor mixture. When quality is 100%, the entire mass is in the vapor phase—there’s no liquid left. That state is dry saturated steam: vapor existing at the saturation temperature for the given pressure, with no liquid in equilibrium. It isn’t superheated steam, since there is still a defined saturation point with no liquid; it isn’t liquid water, and it isn’t a two-phase mixture. So 100% quality corresponds to dry saturated steam.