## GATE ME questions on pure substances

Question #1

The INCORRECT statement about the characteristics of critical point of a pure substance is that
(A) there is no constant temperature vaporization process
(B) it has point of inflection with zero slope
(C) the ice directly converts from solid phase to vapor phase
(D) saturated liquid and saturated vapor states are identical

[GATE 16 S3, 1 mark]

Question #2

For an ideal gas with constant values of specific heats, for calculation of the specific enthalpy,
(A) it is sufficient to know only the temperature
(B) both temperature and pressure are required to be known
(C) both temperature and volume are required to be known
(D) both temperature and mass are required to be known

[GATE 15 S1, 1 mark]

Question #3

A rigid container of volume 0.5 m3 contains 1.0 kg of water at 120°C (v f = 0.00106 m3/kg, vg= 0.8908 m3/kg). The state of water is
(A) compressed liquid
(B) saturated liquid
(C) a mixture of saturated liquid and saturated vapor
(D) superheated vapor

[GATE 15 S3, 1 mark]

Question #4

Steam enters a turbine at 30 bar, 300°C (u = 2750 kJ/kg, h = 2993 kJ/kg) and exits the turbine as saturated liquid at 15 kPa (u = 225 kJ/kg, h = 226 kJ/kg). Heat loss to the surrounding is 50 kJ/kg of steam flowing through the turbine. Neglecting changes in kinetic energy and potential energy, the work output of the turbine (in kJ/kg of steam) is ________

[GATE 15 S3, 2 marks]

Question #5

A pure substance at 8 MPa and 400 °C is having a specific internal energy of 2864 kJ/kg and a specific volume of 0.03432 m3/kg. Its specific enthalpy (in kJ/kg) is _______

[GATE 14 S2, 1 mark]