Thermodynamics – Section 1

11. The processes occurring in an open system which permit the transfer of mass to and from the system, are known as

A. flow processes
B. non-flow processes
C. adiabatic processes
D. none of these

Correct Answer: A. flow processes

12. Which of the following has the minimum atomic mass?

A. Oxygen
B. Sulfur
C. Nitrogen
D. Carbon

Correct Answer: D. Carbon

13. Workdone in a free expansion process is

A. zero
B. minimum
C. maximum
D. positive

Correct Answer: A. zero

14. The pressure exerted by an ideal gas is __________ of the kinetic energy of all the molecules contained in a unit volume of gas.

A. one-half
B. one-third
C. two-third
D. three-fourth

Correct Answer: C. two-third

15. The compression ratio for petrol engines is

A. 3 to 6
B. 5 to 8
C. 15 to 20
D. 20 to 30

Correct Answer: B. 5 to 8

16. The most probable velocity of the gas molecules is given by


Correct Answer: Option B

17. The efficiency of Diesel cycle approaches to Otto cycle efficiency when

A. cut-off is increased
B. cut-off is decreased
C. cut-off is zero
D. cut-off is constant

Correct Answer: C. cut-off is zero

18. The entropy __________ in an irreversible cyclic process.

A. remains constant
B. decreases
C. increases

Correct Answer: C. increases

19. The atomic mass of oxygen is

A. 12
B. 14
C. 16
D. 32

Correct Answer: C. 16

20. The ratio of specific heat at constant pressure (cp) and specific heat at constant volume (cv) is

A. equal to one
B. less than one
C. greater than one
D. none of these

Correct Answer: C. greater than one

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