GATE XE First Law of Thermodynamics PYQs & Answers

Questions 1–10 of 38. Imported answers require independent review unless marked reviewed.

In a mixing chamber hot water enters at a temperature of 80 °C with a flow rate of 0.5 kg/s. From another entry, cold water enters the chamber at 20 °C. The desired temperature after mixing at the exit of the chamber is 40 °C. There is no water leakage and the mixing happens at adiabatic conditions. Assume the specific heat capacity of water is 4.2 kJ/kg-K. For a steady state operation, the mass flow rate (in kg/s) of the cold-water stream is

Your answerChoose one option.

2.0

1.5

1.0

0.5

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An adiabatic rigid and impermeable tank of volume

contains air at 800 kPa and 70 °C. The air is allowed to leave the tank until the pressure is one-fourth of its original value. During the process, the air in the tank is maintained at 70 °C using an electrical heater. Assume that the air behaves as an ideal gas having gas constant and ratio of specific heat capacities as 287 J/kg-K and 1.4, respectively. The total electrical energy (in MJ) supplied by the heater is ____________ (rounded off to two decimal places).

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Two kg of a gas is compressed in a process. Pressure (P) and mass specific volume (v) of the gas during the process follows:

. The temperature of the gas before and after compression is 300 K and 600 K, respectively. Assume that the gas behaves as an ideal gas with gas constant and ratio of specific heat capacities equal to 287 J/kg-K and 1.4, respectively. The heat rejected (in kJ) during the process is ____________ (rounded off to two decimal places).

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A cylinder of volume 0.1 m³ is filled with nitrogen at 10 MPa and 300 K. Consider nitrogen to be an ideal gas. The cylinder develops a leak and nitrogen escapes to atmosphere which is at 0.1 MPa. After some time, the pressure in the cylinder reduces to 5 MPa. Assuming the cylinder and the leaked gas temperature remains constant at 300 K, the work done (in MJ) by nitrogen gas is

Your answerChoose one option.

0.1

0.5

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A closed system undergoes a process 1–2 in which it absorbs 150 kJ of energy as heat and does 90 kJ of work. Then it follows another process 2–3 in which 80 kJ of work is done on it while it rejects 60 kJ as heat. If it is desired to restore the system to the initial state (state 1) by an adiabatic path, the work interaction (in kJ) in this process will be

Your answerChoose one option.

100

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A stream of superheated steam (2 MPa, 300 °C) mixes with another stream of superheated steam (2 MPa, 400 °C) through a steady-state adiabatic process. The flow rates of the streams are 3 kg/min and 2 kg/min, respectively. This mixture then expands in an adiabatic nozzle to a saturated mixture with a quality of 0.77 and 1 kPa. Neglect the velocity at the nozzle entrance and the change in potential energies. The velocity at the nozzle exit (in m/s) is __________ (rounded off to two decimal places).

Use the following data:

At 2 MPa, 300 °C: Specific enthalpy of superheated steam = 3024.2 kJ/kg

At 2 MPa, 400 °C: Specific enthalpy of superheated steam = 3248.4 kJ/kg

At 1 kPa: Specific enthalpy of saturated water = 29.3 kJ/kg

At 1 kPa: Specific enthalpy of saturated vapour = 2513.7 kJ/kg

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A piston-cylinder assembly having 250 mm diameter contains 0.01 kg of water vapor at 1 MPa and 200 °C. The specific volume of the vapor is 0.20602 m

/kg. The system expands as per the relation

= constant, where p is pressure and V is volume. If the final pressure is 0.35 MPa, the value of the exponent (n) is __________ (rounded off to two decimal places).

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A steam boiler contains saturated water vapour at 200 °C. After a certain period, the temperature of the boiler drops to 110 °C. Assume that all the valves of the boiler are closed and the energy is lost as heat to the surroundings. The ratio of mass of liquid to the mass of vapour is ____________ (rounded off to two decimal places).

Saturated volume of vapor phase at 200 °C = 0.127 m

/kg

Saturated volume of vapor phase at 110 °C = 1.210 m

/kg

Saturated volume of liquid phase at 110 °C = 0.001 m

/kg

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The temperature of 10 g of liquid water (

J/g.K) in an insulated container is raised by 5 K by stirring. The amount of heat transferred to the water (in J) is

Your answerChoose one option.

210

420

105

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The figure shows four different processes labeled 1, 2, 3, and 4 for the same closed system containing an ideal gas. The curves labeled

, and

are isotherms. For which one of the four processes, the magnitude of internal energy change is the highest?

Diagram for Engineering Sciences question 91

Your answerChoose one option.

Process 1

Process 2

Process 3

Process 4

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GATE XE First Law of Thermodynamics PYQs

How to practice First Law of Thermodynamics

Question 90

Question 101

Question 102

Question 89

Question 90

Question 103

Question 104

Question 106

Question 90

Question 91