Multiple Choice Questions and Answers (MCQs) on Engineering Thermodynamics
01. When a gas is heated, change takes place in
(A) Temperature
(B) Pressure
(C) Volume
(D) All of these
Answer: Option D
02. One molecule of oxygen consists of ________ atoms of oxygen.
(A) 2
(B) 4
(C) 8
(D) 16
Answer: Option A
03. Which of the following variables controls the physical properties of a perfect gas?
(A) Pressure
(B) Temperature
(C) Volume
(D) All of the above
Answer: Option D
04. The distillation carried out in such a way that the liquid with the lowest boiling point is first evaporated and recondensed, then the liquid with the next higher boiling point is then evaporated and recondensed, and so on until all the available liquid fuels are separately recovered in the sequence of their boiling points. Such a process is called
(A) Cracking
(B) Fractional distillation
(C) Full distillation
(D) Carbonisation
Answer: Option B
05. Work done in a free expansion process is
(A) Zero
(B) Maximum
(C) Minimum
(D) Positive
Answer: Option A
06. Which of the following laws is applicable for the behaviour of a perfect gas?
(A) Boyle’s law
(B) Charles’ law
(C) Gay Lussac’s law
(D) All of the above
Answer: Option D
07. The unit of temperature in S.I. units is
(A) Centigrade
(B) Celsius
(C) Fahrenheit
(D) Kelvin
Answer: Option D
08. A cycle consisting of _________ and two isothermal processes is known as Stirling cycle.
(A) Two isentropic
(B) One constant pressure, one constant volume
(C) Two constant volumes
(D) Two constant pressures
Answer: Option C
09. A tri-atomic molecule consists of __________ atoms.
(A) Three
(B) One
(C) Two
(D) Four
Answer: Option A
10. The unit of mass in S.I. units is
(A) Kilogram
(B) Gram
(C) Tonne
(D) Quintal
Answer: Option A
11. The unit of time in S.I. units is
(A) Second
(B) Minute
(C) Hour
(D) Day
Answer: Option A
12. The unit of length in S.I. units is
(A) Meter
(B) Centimetre
(C) Kilometre
(D) Millimetre
Answer: Option A
13. Mond gas is obtained by
(A) Partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast
(B) Carbonisation of bituminous coal
(C) Passing steam over incandescent coke
(D) Passing air and a large amount of steam over waste coal at about 650°C
Answer: Option D
14. The main cause for the irreversibility is
(A) Unrestricted expansion
(B) Mechanical and fluid friction
(C) Heat transfer with a finite temperature difference
(D) All of the above
Answer: Option D
15. The unit of energy in S.I. units is
(A) watt
(B) Joule
(C) joule/s
(D) joule/m
Answer: Option B
16. According to Dalton’s law, the total pressure of the mixture of gases is equal to
(A) Greater of the partial pressures of all
(B) Average of the partial pressures of all
(C) Sum of the partial pressures of all
(D) Sum of the partial pressures of all divided by average molecular weight
Answer: Option C
17. Which of the following can be regarded as gas so that gas laws could be applicable, within the commonly encountered temperature limits?
(A) O₂, N₂, steam, CO₂
(B) O₂, N₂, water vapour
(C) SO₂, NH₃, CO₂, moisture
(D) O₂, N₂, H₂, air
Answer: Option D
18. The measurement of a thermodynamic property known as temperature is based on
(A) First law of thermodynamics
(B) Second law of thermodynamics
(C) Zeroth law of thermodynamics
(D) None of these
Answer: Option C
19. For a perfect gas, according to Boyle’s law (where P = Absolute pressure, V = Volume and T = Absolute temperature)
(A) V/T = constant, if p is kept constant
(B) P v = constant, if T is kept constant
(C) T/P = constant, if v is kept constant
(D) P/T = constant, if v is kept constant
Answer: Option B
20. The gas turbine cycle with regenerator improves
(A) Work ratio
(B) Thermal efficiency
(C) Avoid pollution
(D) None of these
Answer: Option B
21. The compression ratio is the ratio of
(A) Total volume to swept volume
(B) Swept volume to clearance volume
(C) Swept volume to total volume
(D) Total volume to clearance volume
Answer: Option D
22. The unit of pressure in S.I. units is
(A) kg/cm²
(B) mm of water column
(C) Pascal
(D) Dyne per square cm
Answer: Option C
23. A closed system is one in which
(A) Mass does not cross boundaries of the system, though energy may do so
(B) Mass crosses the boundary but not the energy
(C) Neither mass nor energy crosses the boundaries of the system
(D) Both energy and mass cross the boundaries of the system
Answer: Option A
24. Temperature of a gas is produced due to
(A) Its heating value
(B) Kinetic energy of molecules
(C) Repulsion of molecules
(D) Surface tension of molecules
Answer: Option B
25. According to kinetic theory of gases, the absolute zero temperature is attained when
(A) Volume of the gas is zero
(B) Pressure of the gas is zero
(C) Kinetic energy o
f the molecules is zero
(D) Specific heat of gas is zero
Answer: Option C