GATE XE topic:first-law-thermodynamics PYQs & Answers — Page 2

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Questions 11–20 of 38. Imported answers require independent review unless marked reviewed.

Topic practice 38 questionsPage 2 of 4

A rigid tank, initially at 1 bar and 300 K, contains 5 moles of

, 4 moles of

, and 3 moles of

. From this tank, 2 moles of

are removed keeping the temperature constant. Assuming ideal gas behavior, the final partial pressure of

(in bar) inside the tank is ________ (rounded off to three decimal places).

Use

J/mol.K

Molecular weights of

and

are 2 g/mol, 28 g/mol, and 32 g/mol respectively.

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A fixed mass of an ideal gas undergoes two different cycles M and N as shown in the Pressure (

) – Volume (

) diagrams. Based on the information provided, which one of the following statements is always TRUE?

Diagram for Engineering Sciences question 97

Your answerChoose one option.

Heat input in Cycle M is equal to heat input in Cycle N

Heat rejected in Cycle M is equal to heat rejected in Cycle N

Net heat transfer in Cycle M is equal to net heat transfer in Cycle N

Thermal efficiency of Cycle M is equal to thermal efficiency of Cycle N

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An ideal gas undergoes a series of reversible steady state, steady flow processes between states 1, 2 and 3. Process 1→2 satisfies the relation

, where pressure, P is in kPa and specific volume, v is in m³/kg. Process 2→3 is isobaric. Given that

m³/kg,

, the total work done per unit mass (in kJ/kg) in the series of processes 1→2→3 is ________ (rounded off to the nearest integer).

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Air (assumed as an ideal gas) with a mass flow rate of 2.5 kg/s enters a horizontal nozzle at 350 K, 350 kPa with a velocity of 3 m/s. The air exits the nozzle at a pressure of 101.5 kPa and temperature 305 K with a Mach number of

. Assuming steady state operation and constant properties given in the data, the ratio of inlet area to exit area required to satisfy the exit condition is ________ (rounded off to one decimal place).

Use the following data:

kJ/kg.K,

kJ/kg.K

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A rigid insulated tank containing an ideal gas at 300 K and 1 bar is being filled from an external pressurized line supplying the same gas at 300 K and 10 bar. When the mass of gas inside the tank has doubled, its temperature (in K) is ________ (rounded off to the nearest integer).

Assume ratio of specific heats to be constant for this process and equal to 1.4.

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A piston-cylinder system contains 2 kg of wet steam at 90 °C with quality of 0.1. The piston is loaded with a linear spring. The steam is heated to 800 kPa and 250 °C on heating. The work done (in kJ) in this process is ______ (rounded off to two decimal places).

Use the following data:

At 90 °C:

kPa,

m³/kg,

m³/kg

At 250 °C and 800 kPa:

m³/kg

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A piston-cylinder device initially contains 1 m

of air at 200 kPa and 25 °C. Air expands at constant pressure while a heater of 250 W is switched on for 10 minutes. There is a heat loss of 4 kJ during this process. Assuming air as an ideal gas, the final temperature of air is ______ °C (rounded off to one decimal place).

Use the following data for air:

kJ/kg-K,

kJ/kg-K

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Steam at 2 MPa and 300 °C steadily enters a nozzle of inlet diameter of 20 cm. Steam leaves the nozzle with a velocity of 300 m/s. The mass flow rate of steam through the nozzle is 10 kg/s. Assume no work interaction and no change in potential energy. If the heat loss from the nozzle per kg of steam is 3 kJ, the exit enthalpy per kg of steam is ______ kJ (rounded off to nearest integer).

Use the following data for steam:

At 2 MPa and 300 °C:

/kg,

kJ/kg

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Air in a closed system undergoes a thermodynamic process from an initial temperature of 300 K to the final temperature of 400 K. The specific heat of air at constant volume,

varies linearly with the temperature,

(in K) as

Change in the specific internal energy of the air in the system is ______ kJ/kg (round off to 2 decimal places).

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An insulated rigid tank of volume 10 m³ contains air initially at 1 MPa and 600 K. A valve connected to the tank is opened, and air is allowed to escape until the temperature inside the tank drops to 400 K. The temperature of the discharged air can be approximated as the average of the initial and final temperatures of the air in the tank. Neglect kinetic and potential energies of the discharged air. Assume that air behaves as an ideal gas with constant specific heat so that internal energy

and enthalpy

. Then, the final pressure of the air in the tank is ______ MPa (round off to 2 decimal places).

Assume

kJ/(kg K),

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GATE XE topic:first-law-thermodynamics PYQs

Question 96

Question 97

Question 104

Question 105

Question 108

Question 109

Question 101

Question 102

Question 93

Question 103