Previous Years GATE Solved MCQs on Basics of Thermodynamics

GATE Solved Questions on Basics of Thermodynamics 

Basic Thermodynamics is a very important topic for the GATE Preparation. Here are Some GATE questions based on the basic thermodynamics. The questions are accompanied with hints, solutions and answers. 

Question 1. A small steam whistle (perfectly insulated and doing no shaft work) causes a drop of 0.8 kJ/kg in enthalpy of steam from entry to exit. The kinetic energy of the steam at entry is negligible, the velocity of steam at exit is

(A) 4 m/s

(B) 40 m/s

(C) 80 m/s

(D) 120 m/s

GATE-ME-2001

Hint

Question 2. What is the speed of sound in Neon gas at a temperature of 500 K (gas constant of neon is 0.4210 kJ/kg-k)?

(A) 492 m/s

(B) 460 m/s

(C) 592 m/s

(D) 543 m/s

GATE-ME-2002

Hint

Question 3. A reversible thermodynamic cycle containing only three processes and producing work is to be constructed. The constraints are

(i) There must be one isothermal process,

(ii) There must be one isentropic process,

(iii) The maximum and minimum cycle pressure and the clearance volume are fixed,

(iv) Polytropic processes are not allowed.

Then the number of possible cycles are

(A) 1

(B) 2

(C) 3

(D) 4

GATE-ME-2005

Hint

Question 4. The following four figures have been drawn to represent a fictitious thermodynamic cycle, on the P-V and T-S planes.

According to the first law of thermodynamics, equal areas are enclosed by

(A) Fig 1 and 2

(B) Fig 1 and 3

(3) Fig 1 and 4

(4) Fig 2 and 3

GATE-ME-2005

Hint

Statement for linked Answer Question 5 & 6.

A football was inflated to a gauge pressure 1 bar when the ambient temperature was . When the game started next day, the air temperature at the stadium is . Assume that the volume of the ball remains constant at 

Question 5. The amount of the heat lost by the air in the football and the gauge pressure of air in the football at the stadium respectively is

(A) 30.6 J, 1.94 bar

(B) 21.8, 0.93 bar

(C) 61.1 J, 1.94 bar

(D) 43.7 J, 0.93 bar

GATE-ME-2006

Hint

Question 6. Gauge pressure of air to which the ball must have been originally inflated so that it would equal 1 bar gauge at the stadium is

(A) 2.23 bar

(B) 1.94 bar

(C) 1.07 bar

(D) 1.00 bar

GATE-ME-2006

Hint

Question 7. Which of the following relationship is valid only for reversible process undergone by a closed system of simple compressible substance (neglect changes in kinetic and potential energy)?

(A) 

(B) 

(C) 

(D) 

GATE-ME-2007

Hint

Question 8. In a steady state flow process taking place in a device with a single inlet and a single outlet, the work done per unit mass flow rate is given by , where  is the specific volume and p is the pressure. The expression for w given above

(A) is valid only if the process is both reversible and adiabatic

(B) Is valid only if the process is both reversible and isothermal

(C) Is valid for any reversible process

(D) Is incorrect; it must be 

GATE-ME-2008

Hint

Question 9. A rigid, insulated tank is initially evacuated. The tank is connected with a supply line through which air (assumed to be ideal gas with constant specific heats) passes at 1 MPa, . A valve connected with the supply line is opened and the tank is charged with air until the final pressure inside the tank reaches 1 MPa. The final temperature inside the tank

(A) Is greater than 

(B) Is less thsn 

(C) Is equal to 

(D) May be greater than, less than, or equal to , depending on the volume of the tank

GATE-ME-2008

Hint

Question 10. A balloon containing an ideal gas is initially kept in an evacuated and insulated room. The balloon ruptures and the gas fills up the entire room. Which one of the following statement is true at the end of the above process?

(A) The internal energy of the gas decreases from its initial value, but the enthalpy remains constant

(B) The internal energy of the gas increases from its initial value, but the enthalpy remains constant

(C) Both internal energy and enthalpy of the gas remains constant

(D) Both internal energy and the enthalpy of the gas increase

GATE-ME-2008

Hint

Question 11. A compressor undergoes a reversible, steady flow process. The gas at inlet and outlet of the compressor is designated as state 1 and state 2 respectively. Potential and kinetic energy changes are to be ignored. The following notations are used:

V=specific volume and P= pressure of the gas.

The specific work required to be supplied to the compressor for this gas compression process is

(A) 

(B) 

(C) 

(D) 

GATE-ME-2009

Hint

Question 12. Heat and work are

(A) Intensive properties

(B) Extensive properties

(C) Point functions

(D) Path functions

GATE-ME-2011

Hint

Question 13. The contents of a well- insulated tank are heated by a resistor of 23 Ω in which 10 A current is flowing. Consider the tank with its contents as a thermodynamic system. The work done by the system and the heat transfer to the system are positive. The rates of heat (Q), work (W) and change in () during the process in KW are

(A) Q=0, W=-2.3,=+2.3

(B) Q=+2.3, W=0, =+2.3

(C) Q=-2.3, W=0, =-2.3

(D) Q=0, W=2.3, =-2.3

GATE-ME-2011

Hint

Question 14. Steam enters an adiabatic turbine operating at steady state with an enthalpy of 3251.0 kJ/kg respectively. The mass flow rate of steam is 10 kg/s. kinetic and potential energy changes are negligible. The power output of the turbine in MW is

(A) 6.5

(B) 8.9

(C) 9.1

(D) 27.0

GATE-ME-2012

Hint

Statement for Linked Answer  Question 15 and 16

Air enters an adiabatic nozzle at 300 kPa, 500 K with a velocity of 10 m/s. it leaves the nozzle at 100 kPa with a velocity of 180 m/s. The inlet area is . The specific heat of air  is 1008 J/kg K

Question 15. The exit temperature of the air is

(A) 516 K

(B) 532 K

(C) 484 K

(D) 468 K

GATE-ME-2012

Hint

Question 16. The exit area of the nozzle in  is

(A) 90.1

(B) 56.3

(C) 4.4

(D) 12.9

GATE-ME-2012

Hint

Question 17. A cylinder contains 5  of an ideal gas at a pressure of 1 bar. This gas is compressed in a reversible isothermal process till its pressure increases to 5 bar. The work in kJ required for this process is

(A) 804.7

(B) 953.2

(C) 981.7

(D) 1012.2

GATE-ME-2013

Hint

Question 18. Specific enthalpy and velocity of steam at inlet and exit of a steam turbine running under steady state are as given below:

The rate of heat loss from the turbine per kg of steam flow rate is 5 kW. Neglecting changes in potential energy of steam, the power developed in kW by the steam turbine per kg of steam flow rate, is

(A) 901.2

(B) 911.2

(C) 17072.5

(D) 17082.5

GATE-ME-2013

Hint

Question 19. The pressure, temperature and velocity of air flowing in a pipe are 5 bar, 500 K and 50 m/s, respectively. The specific heats of air at constant pressure and at constant volume are 1.005 kJ/kg K and 0.718 kJ/kg K respectively. Neglect potential energy. If the pressure and temperature of the surrounding are 1 bar, 300 K  respectively, the available energy in kJ/kg of the air steam is

(A) 170

(B) 191

(C) 187

(D) 213

GATE-ME-2013

Hint

Answer keys

1. (B)     2. (D)     3. (D)     4. (A)     5. (D)     6. (C)     7. (C)     8. (C)     9. (A)     10. (C)   11. (B)   12. (D)   13. (B)   14. (B)   15. (C)   16. (D)   17. (A)   18. (A)   19 (B)