Engineering Thermodynamics Questions And Answers - Set 18 - ObjectiveBooks

# Practice Test: Question Set - 18

1. When the expansion or compression takes place according to the law pvn = C, the process is known as
(A) Isothermal process
(C) Hyperbolic process
(D) Polytropic process

2. The general law of expansion or compression is pvn = C, The process is said to be hyperbolic, if n is equal to
(A) 0
(B) 1
(C) γ
(D) ∝

3. One kilowatt is equal to
(A) 1 N-m/s
(B) 100 N-m
(C) 1000 N-m/s
(D) 1 × 106 N-m/s

4. The __________ states that change of internal energy of a perfect gas is directly proportional to the change of temperature.
(A) Boyle's law
(B) Charle's law
(C) Gay-Lussac law
(D) Joule's law

5. The amount of heat required to raise the temperature of __________ water through one degree is called kilojoules.
(A) 1 g
(B) 10 g
(C) 100 g
(D) 1000 g

6. The work ratio of a gas turbine plant is given by
(A) (Net work output)/(Work-done by the turbine)
(B) (Net work output)/(Heat supplied)
(C) (Actual temperature drop)/(Isentropic temperature drop)
(D) (Isentropic increase in temperature)/(Actual increase in temperature)

7. The variables which control the physical properties of a perfect gas are
(A) Pressure exerted by the gas
(B) Volume occupied by the gas
(C) Temperature of the gas
(D) All of these

8. An open system is one in which
(A) Heat and work crosses the boundary of the system, but the mass of the working substance does not crosses the boundary of the system
(B) Mass of the working substance crosses the boundary of the system but the heat and work does not crosses the boundary of the system
(C) Both the heat and work as well as mass of the working substance crosses the boundary of the system
(D) Neither the heat and work nor the mass of the working substance crosses the boundary of the system

9. Which of the following statement is correct?
(A) The increase in entropy is obtained from a given quantity of heat at a low temperature.
(B) The change in entropy may be regarded as a measure of the rate of the availability or unavailability of heat for transformation into work.
(C) The entropy represents the maximum amount of work obtainable per degree drop in temperature.
(D) All of the above

10. The calorific value of gaseous fuel is expressed in
(A) kJ
(B) kJ/kg
(C) kJ/m2
(D) kJ/m3

11. Which of the following is the correct statement of the second law of thermodynamics?
(A) It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work.
(B) It is impossible to transfer heat from a body at a lower temperature to a higher temperature, without the aid of an external source.
(C) There is a definite amount of mechanical energy, which can be obtained from a given quantity of heat energy.
(D) All of the above

12. 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

13. The expansion ratio (r) is the ratio of (where v1 = Volume at the beginning of expansion, and v2 = Volume at the end of expansion)
(A) v1/v2
(B) v2/v1
(C) (v1 + v2)/v1
(D) (v1 + v2)/v2

14. Coke is produced
(A) When coal is first dried and then crushed to a fine powder by pulverizing machine
(B) From the finely ground coal by molding under pressure with or without a binding material
(C) When coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel
(D) By heating wood with a limited supply of air to a temperature not less than 280°C

15. The hard coke is obtained when carbonization of coal is carried out at
(A) 300° to 500°C
(B) 500° to 700°C
(C) 700° to 900°C
(D) 900° to 1100°C

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