The GATE Grind

GATE 2018 ME (ME1) – Question 20

Thermodynamics · Thermodynamic systems and processes, properties of pure substances · 1 mark · Multiple choice

Which is correct for superheated vapour?

  1. Its pressure is below saturation pressure at the same temperature.
  2. Its temperature is below saturation temperature at the same pressure.
  3. Its volume is below saturated-vapour volume at the same temperature.
  4. Its enthalpy is below saturated-vapour enthalpy at the same pressure.

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (A) Its pressure is below saturation pressure at the same temperature.

Explanation

At fixed temperature, superheated vapour lies below the saturation pressure, so **A** is correct. At fixed pressure its temperature and enthalpy exceed saturated-vapour values. The liquid–vapour saturation relation defines the boundary of the superheated region.