Question

If the temperature of a saturated water is increased infinitesimally at constant entropy, the resulting state of water is:

• A. Liquid
• B. Liquid–vapor co-existence
• C. Saturated vapor
• D. Solid

Hint:

At constant entropy, heating saturated liquid leads to phase change into saturated vapor.

Answer 1

The Correct Option is C

Step 1: Phase Equilibrium Recall.
At saturation, liquid and vapor water coexist in equilibrium. An increase in temperature at constant entropy indicates a phase transition.

Step 2: Isentropic Transition.
With constant entropy (isentropic process), the water fully converts to saturated vapor.

Step 3: Final Determination.
Therefore, the correct classification is (C) saturated vapor.