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Basic Concepts & Zeroth Law of Thermodynamics 4

61. Thermocouples are generally used for measuring temperature:
 (a) 500°C            (b) 1000 °C
 (c) 1500°C          (d) 2000°C
SJVN ET 2013 TNPSC AE 2018 
Ans. (c) : Thermocouples are generally used for measuring temperature up to 1500oC

 62. Which of the following is not a point function of the system. 
 (a) Temperature         (b) Pressure 
 (c) Specific volume     (d) Heat 
TRB Polytechnic Lecturer 2017 
Ans. (d) : Heat is path function whereas temperature, pressure and specific volume are point function.

63. The enthalpy of an ideal gas is a function of 
 (a) Pressure only             (b) Volume only 
 (c) Temperature only       (d) None of these
 Nagaland PSC CTSE 2017 Paper-2
 Ans. (c) : Enthalpy is a function of temperature only. 

64. 1ºC is equal to 
 (a) 273.15 K         (b) 274.15 K 
 (c) 283.15 K         (d) 263.15 K 
Nagaland PSC CTSE 2017 Paper-2 
Ans. (b) : 1ºC is equal to Kelvin, 274.15 K.  

65. Identify open system and closed system from the following
 (a) Blood circulation and respiration in human body
 (b) Fuel system and radiator in cars 
 (c) Air compressor and boiler 
 (d) Shell and tube heat exchanger and Blower 
Nagaland PSC CTSE 2017 Paper-2
 Ans. (c) : Air compressor is an open system and boiler comes under closed system (boiler having closed chamber).

 66. Compression efficiency is compared against 
 (a) Ideal compression
 (b) Adiabatic compression 
 (c) Isentropic compression 
 (d) Isothermal compression 
Nagaland PSC CTSE 2017 Paper-2
 Ans. (d) : Compression efficiency is compared against isothermal compression. 

67. Which thermometer is independent of the substance or material used in its construction? 
 (a) mercury thermometer 
 (b) alcohol thermometer
 (c) ideal gas thermometer 
 (d) resistance thermometer 
Nagaland PSC CTSE 2017 Paper-2 
Ans. (c) : Ideal gas thermometer in independent of the substance or material used in its construction. 

68. The pressure of air in an automobile tyre at temperature of 27ºC is 1.75 bar (gauge). Due to running the temperature of air in the rises to 87ºC. What will be the gauge pressure during this running? [Patm = 1.01 bar, volume of tyre is assumed constant] 
(a) 2.302 bar         (b) 2.914 bar
 (c) 1.677 bar        (d) 3.180 bar
SJVN ET 2019 
Ans. (a) : Pabs = Patm + Pgauge 
                      = 1.01 + 1.75
                      = 2.76 bar
Use Ideal gas equation,
                   (P1V1)/T1 = (P2V2)/T2

69. A non-flow reversible process takes place according to V = 15/P m^3 , P = where P is in bar. What will be the work done if pressure changes from 1 bar to 10 bar? [Given. ln (10) = 2.3025] 

 (a) 3.453 MN-m, expansion 
 (b) 3.453 N-m, compression 
 (c) 3.453 MN-m compression 
 (d) 3.453 N-m, expansion
 SJVN ET 2019
Ans. (c) 

70. In a steady flow reversible adiabatic process work done is equal to 
(a) Change in internal energy 
 (b) Change in entropy 
 (c) Change in enthalpy
 (d) Heat transferred 
TNPSC AE 2014
 Ans. (c) : In a steady flow reversible adiabatic process work done is equal to change in enthalpy. 

71. Certain quantities cannot be located on the graph by a point but are given by a point but are given by the area under the curve corresponding to the process. These quantities in concepts of thermodynamics are called as
 (a) cyclic functions         (b) point functions 
 (c) path functions           (d) real functions 
ESE 2019 
Ans. (c) : Path functions like heat transfer and work done cannot be represented by points in the graph, but can be given by the area under the curve. Heat transfer will be area under curve in T-s diagram while work done will be the area under curve in p-v diagram. 

72. A steel tank placed in hot environment contains 5 kg of air at 4atm at 30°C. A portion of the air is released till the pressure becomes 2 atm. Later, the temperature of the air in the tank is found to be 150°C. The quantity of air allowed to escape is 
 (a) 4.72 kg         (b) 4.12 kg 
 (c) 3.71 kg         (d) 3.21 kg
 ESE 2018 
Ans. (d)

73. The thermal efficiency of the hypothetical cycle shown is 
 (a) 0.6         (b) 0.5
 (c) 0.4         (d) 0.3
 ESE 2017 
Ans. (c)
 


74. If the compression or expansion of a gas takes place in such a way that the gas neither gives heat nor takes heat from its surroundings, the process is said to be 
(a) Isothermal         (b) Adiabatic 
(c) Isobaric             (d) None of these 
APPSC AEE 2012 
Ans : (b) If the compression or expansion of a gas takes place in such a way that the gas neither gives heat nor takes heat from its surrounding, the process is said to be adiabatic. 

75. For an adiabatic process, 
 (a) PV = a constant             (b) PV^n = a constant
 (c) P/(ρ^γ) =a constant           (d) P/(K^ρ) = a constant 
 APPSC 2012
 Ans : (c) For an adiabatic process
              
 γ = Ratio of the specific heat at constant pressure to the specific heat at Constant volume. 
            . 

76. The equation PV = mRT is essentially valid for 
 (a) Perfect gas                 (b) Real gas
 (c) Monoatomic gas         (d) Mixture of gases 
(KPSC AE 2015) 
Ans : (a) The equation PV = mRT is essentially valid for perfect gas. 
The equation PV = mRT may also be expressed in another form
                     

77. The weight of oxygen in atmospheric air is 
 (a) 21%             (b) 19%
 (c) 23%             (d) 31% 
(KPSC AE 2015)
 Ans : (c) The weight of oxygen in atmospheric air 23% 

78. The characteristic equation of gases  holds good for 
 (a) Monoatomic gases        (b) diatomic gases
 (c) real gases                     (d) ideal gases 
BPSC Poly. Lect. 2016
 Ans : (d)

79. Orsat apparatus is used for analyzing......... 
 (a) oxygen                 (b) air 
 (c) carbon dioxide       (d) flue gases 
(HPPSC LECT. 2016) 
Ans : (d) Orsat apparatus is used for analyzing flue gases. 

80. A closed system is one which 
 (a) permits the passage of energy and matter across the boundaries.
 (b) does not permit the passage of energy and matter across the boundaries.
 (c) permit the passage of energy across the boundary but does not permit the passage of matter. 
 (d) permit the passage of energy across the boundary but does not permit the passage of matter. 
TSPSC AEE 2015 
Ans : (c)

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