Engineering Thermodynamics Solved MCQs
| 1. | A definite area or space where some thermodynamic process takes place is known as |
| A. | thermodynamic system |
| B. | thermodynamic cycle |
| C. | thermodynamic process |
| D. | thermodynamic law |
| Answer» A. thermodynamic system | |
| 2. | An open system is one in which |
| A. | heat & work cross the boundary of the system, but the mass of the working substance does not |
| B. | mass of working substance crosses the boundary of the system but the heat & work do not |
| C. | both the heat & work as well as mass of the working substance cross the boundary of the system |
| D. | neither the heat & work nor the mass of the working substances cross the boundary of the system |
| Answer» C. both the heat & work as well as mass of the working substance cross the boundary of the system | |
| 3. | An isolated system |
| A. | is a specified region where transfer of energy and/or mass take place |
| B. | is a region of constant mass & only energy is allowed to cross the boundaries |
| C. | cannot transfer either energy or mass to or from the surroundings |
| D. | is one in which mass within the system is not necessarily constant |
| Answer» C. cannot transfer either energy or mass to or from the surroundings | |
| 4. | Which of the following is an intensive property of a thermodynamic system |
| A. | volume |
| B. | temperature |
| C. | mass |
| D. | energy |
| Answer» B. temperature | |
| 5. | Which of the following is the extensive property of a thermodynamic system |
| A. | pressure |
| B. | volume |
| C. | temperature |
| D. | density |
| Answer» B. volume | |
| 6. | When two bodies are in thermal equilibrium with a third body they are also in thermal equilibrium with each other. This statement is called |
| A. | zeroth law of thermodynamics |
| B. | first law of thermodynamics |
| C. | second law of thermodynamics |
| D. | kelvin planck’s law |
| Answer» A. zeroth law of thermodynamics | |
| 7. | The temperature at which the volume of a gas becomes zero is called |
| A. | absolute scale of temperature |
| B. | absolute zero temperature |
| C. | absolute temperature |
| D. | none of the above |
| Answer» B. absolute zero temperature | |
| 8. | The value of one bar (in SI units) is equal to |
| A. | 100 n/m?? |
| B. | 1000 n/m?? |
| C. | 1??10⁴ n/m?? |
| D. | 1??10⁵ n/m?? |
| Answer» D. 1??10⁵ n/m?? | |
| 9. | The absolute zero pressure will be |
| A. | when molecular momentum of the systembecomes zero |
| B. | at sea level |
| C. | at the temperature of -273 k |
| D. | under vaccum conditions |
| Answer» A. when molecular momentum of the systembecomes zero | |
| 10. | Absolute zero temperature is taken as |
| A. | -273°c |
| B. | 273°c |
| C. | 237°c |
| D. | -373°c |
| Answer» A. -273°c | |
| 11. | Which of the following is correct? |
| A. | absolute pressure= guage pressure+ atmosphericpressure |
| B. | guage pressure= absolute pressure + atmosphericpressure |
| C. | atmospheric pressure= absolute pressure+ guagepressure |
| D. | absolute pressure= guage pressure-atmospheric pressure |
| Answer» A. absolute pressure= guage pressure+ atmosphericpressure | |
| 12. | The unit of energy in SI units is |
| A. | joule (j) |
| B. | joule metre (jm) |
| C. | watt (w) |
| D. | joule/metre (j/m) |
| Answer» A. joule (j) | |
| 13. | One watt is equal to |
| A. | 1 nm/s |
| B. | 1n/min |
| C. | 10 n/s |
| D. | 100 nm/s |
| Answer» A. 1 nm/s | |
| 14. | One joule (J) is equal to |
| A. | 1 nm |
| B. | knm |
| C. | 10 nm/s |
| D. | 10 knm/s |
| Answer» A. 1 nm | |
| 15. | A series of operations, which take place in a certain order & restore the initial condition is known as |
| A. | reversible cycle |
| B. | irreversible cycle |
| C. | thermodynamic cycle |
| D. | none of the above |
| Answer» C. thermodynamic cycle | |
| 16. | The condition for the reversibility of a cycle is |
| A. | the pressure & temperature of the working substance must not differ, appreciably, from those of |
| B. | all the processes, taking place in the cycle of operation, must be extremely slow |
| C. | the working parts of the engine must be friction free |
| D. | all of the above |
| Answer» D. all of the above | |
| 17. | According to kinetic theory of heat |
| A. | temperature should rise during boiling |
| B. | temperature should fall during freezing |
| C. | at low temperature all bodies are in solid state |
| D. | at absolute zero there is absolutely no vibration ofmolecules |
| Answer» D. at absolute zero there is absolutely no vibration ofmolecules | |
| 18. | A system comprising a single phase is called a |
| A. | closed system |
| B. | open system |
| C. | isolated system |
| D. | homogeneous system |
| Answer» D. homogeneous system | |
| 19. | If all the variables of a stream are independent of time it is said to be in |
| A. | steady flow |
| B. | unsteady flow |
| C. | uniform flow |
| D. | closed flow |
| Answer» A. steady flow | |
| 20. | A control volume refers to |
| A. | a fixed region in space |
| B. | a specified mass |
| C. | an isolated system |
| D. | a reversible process only |
| Answer» A. a fixed region in space | |
| 21. | Internal energy of a perfect gas depends on |
| A. | temperature, specificheats & pressure |
| B. | temperature, specificheats & enthalpy |
| C. | temperature, specific heats& entropy |
| D. | temperature only |
| Answer» D. temperature only | |
| 22. | Steady flow process requires that |
| A. | conditions do not change with time at any point |
| B. | conditions are the same at adjacent points at anyinstant |
| C. | conditions change steadily with the time |
| D. | is constant |
| Answer» A. conditions do not change with time at any point | |
| 23. | The first law of thermodynamics for steady flow |
| A. | accounts for all energy entering & leaving a controlvolume |
| B. | is an energy balance for a specified mass of fluid |
| C. | is an expression of the conservation of linearmomentum |
| D. | is primarily concerned with heat transfer |
| Answer» A. accounts for all energy entering & leaving a controlvolume | |
| 24. | Which of the following is not a property of the system |
| A. | temperature |
| B. | pressure |
| C. | specific volume |
| D. | heat |
| Answer» D. heat | |
| 26. | Which one of the following statements is correct? |
| A. | pressure is an extensiveproperty |
| B. | density is an intensiveproperty |
| C. | density is an extensiveproperty |
| D. | temperature is anextensive property |
| Answer» B. density is an intensiveproperty | |
| 27. | First law of thermodynamics deals with conservation of |
| A. | mass |
| B. | momentum |
| C. | energy |
| D. | heat |
| Answer» C. energy | |
| 28. | Which one of the following processes or systems does not involve heat |
| A. | steady processes |
| B. | isothermal processes |
| C. | adiabatic processes |
| D. | thermal processes |
| Answer» C. adiabatic processes | |
| 29. | Thermodynamic equillibrium is completely defined by the specification of |
| A. | generalised displacements |
| B. | internal energy |
| C. | enthalpy |
| D. | all of the above |
| Answer» D. all of the above | |
| 30. | ………. Is not a property of the system |
| A. | pressure |
| B. | temperature |
| C. | heat |
| D. | specific volume |
| Answer» C. heat | |
| 31. | In which of the following processes the external work done is not zero? |
| A. | throttling |
| B. | free expansion |
| C. | constant volume process |
| D. | constant pressureprocess |
| Answer» D. constant pressureprocess | |
| 32. | The extension & compression of a helical spring is an example of |
| A. | irreversible process |
| B. | reversible process |
| C. | isothermal process |
| D. | adiabatic process |
| Answer» B. reversible process | |
| 33. | In all irrevesible processes, the entropy of the system |
| A. | remains unaltered |
| B. | reduces to zero |
| C. | increases |
| D. | none of the above |
| Answer» C. increases | |
| 34. | Temperature of a gas is produced due to which of the following? |
| A. | attraction of molecules |
| B. | repulsion of molecules |
| C. | kinetic energy of molecules |
| D. | all of the above |
| Answer» C. kinetic energy of molecules | |
| 35. | The same volume of all gases at same temperatureand pressure would represent their |
| A. | specific gravity |
| B. | densities |
| C. | specific weights |
| D. | molecular weights |
| Answer» D. molecular weights | |
| 36. | First law of thermodynamics gives relationship between which of the following? |
| A. | heat & internal energy |
| B. | heat & work |
| C. | heat, work & properties of the system |
| D. | various thermodynamics processes |
| Answer» C. heat, work & properties of the system | |
| 37. | The temperature in a process in which work is done by expanding a gas under adiabatic condition will |
| A. | decrease |
| B. | increase |
| C. | first decrease & then increase |
| D. | remain unaltered |
| Answer» A. decrease | |
| 38. | On which of the following laws measurement of temperature is based? |
| A. | joule’s law |
| B. | zeroth law of thermodynamics |
| C. | first law of thermodynamics |
| D. | second law of thermodynamics |
| Answer» B. zeroth law of thermodynamics | |
| 39. | The perpetual motion of the first kind is represented by which of the following? |
| A. | a machine that continuously creates itsown energy |
| B. | an engine with 100 percent efficiency |
| C. | a fully reversible engine |
| D. | none of the above |
| Answer» A. a machine that continuously creates itsown energy | |
| 40. | Which of the following statements regarding a perpetual motion machine is correct? |
| A. | it is an in efficient machine |
| B. | it is non-thermodynamic machine |
| C. | it is thermodynamic machine |
| D. | it is hypothetic machine whose operation would violate the laws of thermodynamics |
| Answer» D. it is hypothetic machine whose operation would violate the laws of thermodynamics | |
| 41. | Which of the following statements, regarding a property of system, is correct? |
| A. | it is path function |
| B. | it is a point function |
| C. | it is always of intensive type |
| D. | none of the above |
| Answer» B. it is a point function | |
| 42. | ……….. Is an intensive property |
| A. | specific volume |
| B. | total volume |
| C. | total mass |
| D. | total energy of a system |
| Answer» A. specific volume | |
| 43. | A system is said to be in thermodynamic equilibrium if it is in |
| A. | chemical equilibrium |
| B. | thermal equilibrium |
| C. | mechanical equilibrium |
| D. | all of the above |
| Answer» D. all of the above | |
| 44. | The basis for measuring thermodynamic property of temperature is given by ……. Law of thermodynamics |
| A. | zeroth |
| B. | first |
| C. | second |
| D. | third |
| Answer» A. zeroth | |
| 45. | As differentials, heat & work would be described mathematically as |
| A. | exact |
| B. | inexact |
| C. | point function |
| D. | discontinuity |
| Answer» B. inexact | |
| 46. | Which of the following is an open thermodynamic system? |
| A. | pressure cooker |
| B. | manual ice cream freezer |
| C. | centrifugal pump |
| D. | none of the above |
| Answer» C. centrifugal pump | |
| 47. | ……… is a non-quasistatic process |
| A. | free expansion of gas |
| B. | expansion of gas in a cylinder under constantpressure |
| C. | rapid leakage of air from a bicycle tyre |
| D. | gradual compression of gas inside a piston-cylinderarrangement |
| Answer» A. free expansion of gas | |
| 48. | Choose the correct statement |
| A. | pressure, temp. &entropy are extensive properties |
| B. | pressure, temp. &entropy are intensive properties |
| C. | pressure, volume & temp. are extensive properties |
| D. | volume & entropy are extensive properties |
| Answer» D. volume & entropy are extensive properties | |
| 49. | The first law of thermodynamics defines |
| A. | entropy |
| B. | internal energy |
| C. | work |
| D. | heat |
| Answer» B. internal energy | |
| 51. | The main cause of the irreversibility is |
| A. | mechanical & fluid friction |
| B. | unrestricted expansion |
| C. | heat transfer with a finite temperature difference |
| D. | all of the above |
| Answer» D. all of the above | |
| 52. | An isentropic process is always |
| A. | irreversible & adiabatic |
| B. | reversible & isothermal |
| C. | frictionless & irreversible |
| D. | reversible & adiabatic |
| Answer» D. reversible & adiabatic | |
| 53. | In the polytropic process equation pvⁿ = constant, if n is infinitely large, the process is termed as |
| A. | constant volume |
| B. | constant pressure |
| C. | constant temperature |
| D. | diabatic |
| Answer» A. constant volume | |
| 54. | Second law of thermodynamics defines |
| A. | heat |
| B. | work |
| C. | enthalpy |
| D. | entropy |
| Answer» D. entropy | |
| 55. | For a reversible adiabatic process, the change in entropy is |
| A. | zero |
| B. | minimum |
| C. | maximum |
| D. | infinite |
| Answer» A. zero | |
| 56. | For any reversible process, the change in entropy of the system & surroundings is |
| A. | zero |
| B. | unity |
| C. | negative |
| D. | positive |
| Answer» A. zero | |
| 57. | For any irreversible process the net entropy change is |
| A. | zero |
| B. | positive |
| C. | negative |
| D. | infinite |
| Answer» B. positive | |
| 58. | The processes of a Carnot cycle are |
| A. | two adiabatic & two constant volume |
| B. | one constant volume &one constant pressure & two isentropies |
| C. | two adiabatics & two isothermals |
| D. | two isothermals & two isentropies |
| Answer» D. two isothermals & two isentropies | |
| 59. | Isentropic flow is |
| A. | irreversible adiabatic flow |
| B. | ideal fluid flow |
| C. | reversible adiabatic flow |
| D. | frictionless reversible flo |
| Answer» C. reversible adiabatic flow | |
| 60. | In a carnot engine, when the working substance gives heat to the sink |
| A. | the temperature of the sink increases |
| B. | the temperature of the sink remains the same |
| C. | the temperature of the source decreses |
| D. | the temperature of the source decrease |
| Answer» B. the temperature of the sink remains the same | |
| 61. | If the temperature of the source is increased, the efficiency of the Carnot engine |
| A. | decrease |
| B. | increase |
| C. | does not change |
| D. | will be equal to the efficiency of a practicalengine |
| Answer» B. increase | |
| 62. | The efficiency of an ideal Carnot engine depends on |
| A. | working substance |
| B. | on the temperature of the source only |
| C. | on the temperature of the sink only |
| D. | on the temperatures of both the source & the sink |
| Answer» D. on the temperatures of both the source & the sink | |
| 63. | In a reversible cycle, the entropy of the system |
| A. | increases |
| B. | decreases |
| C. | does not change |
| D. | first increases & thendecreases |
| Answer» C. does not change | |
| 64. | Kelvin-Plank’s law deals with |
| A. | conservation of energy |
| B. | conservation of heat |
| C. | conservation of mass |
| D. | conversion of heat intowork |
| Answer» D. conversion of heat intowork | |
| 65. | Which of the following statements is correct according to Clausius statement of second law of thermodynamics? |
| A. | it is impossible to transfer heat from a body at a lower temperature to a body at a higher temperature |
| B. | it is impossible to transfer heat from a body at a lower temperature to a body at a higher temperature, without the aid of an external source |
| C. | it is possible to transfer heat from a body at a lower temperature to a body at a higher temperature by using refrigeration cycle |
| D. | none of the above |
| Answer» B. it is impossible to transfer heat from a body at a lower temperature to a body at a higher temperature, without the aid of an external source | |
| 66. | The property of a working substance which increases or decreases as the heat is supplied or removed in a reversible manner is known as |
| A. | enthalpy |
| B. | internal energy |
| C. | entropy |
| D. | external energy |
| Answer» C. entropy | |
| 67. | The entropy may be expressed as a function of |
| A. | pressure & temperature |
| B. | temperature & volume |
| C. | heat & work |
| D. | all of the above |
| Answer» A. pressure & temperature | |
| 68. | The change of entropy when heat is absorbed by the gas is |
| A. | positive |
| B. | negative |
| C. | positive or negative |
| D. | all of the above |
| Answer» A. positive | |
| 69. | Which of the following statements 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 of heat fortransformation into work |
| C. | the entropy represents the maximum amount of work obtainable per degree drop in temperature |
| D. | all of the above |
| Answer» D. all of the above | |
| 70. | In an irreversible process, there is a |
| A. | loss of heat |
| B. | no loss of work |
| C. | gain of heat |
| D. | no gain of heat |
| Answer» A. loss of heat | |
| 71. | The efficiency of the Carnot cycle may be increased by |
| A. | increasing the highesttemperature |
| B. | decreasing the highesttemperature |
| C. | increasing the lowesttemperature |
| D. | decreasing the lowesttemperature |
| Answer» D. decreasing the lowesttemperature | |
| 72. | Which of the following is the correct statement? |
| A. | all the reversible engines have the same efficiency |
| B. | all the reversible & irreversible engines have the same efficiency |
| C. | irreversible engines have maximum efficiency |
| D. | all engines are designed as reversible in order to obtain maximum efficiency |
| Answer» A. all the reversible engines have the same efficiency | |
| 73. | The reversible engines are |
| A. | least efficient |
| B. | most efficient |
| C. | having same efficiency asirreversible engines |
| D. | none of the above |
| Answer» B. most efficient | |
| 74. | Gases could have an infinite number of specific heats but only ……. Specific heats are defined |
| A. | one |
| B. | two |
| C. | three |
| D. | four |
| Answer» B. two | |
| 76. | Second law of thermodynamics defines |
| A. | work |
| B. | heat |
| C. | entropy |
| D. | internal energy |
| Answer» C. entropy | |
| 77. | For storing a gas which one of the following types of compression will be ideal |
| A. | constant volume |
| B. | polytropic |
| C. | adiabatic |
| D. | isothermal |
| Answer» D. isothermal | |
| 78. | A process which can be stopped at any stage & reversed so that the system & the surroundings are exactly restored to their initial states is known as |
| A. | thermodynamic process |
| B. | irreversible process |
| C. | reversible process |
| D. | isothermal process |
| Answer» C. reversible process | |
| 79. | Which of the following is a reversible process? |
| A. | throttling |
| B. | combustion |
| C. | free expansion |
| D. | extension &compression of a spring |
| Answer» D. extension &compression of a spring | |
| 80. | Leaking of air from a punctured tube is an example of |
| A. | isothermal expansion |
| B. | adiabatic expansion |
| C. | throttling |
| D. | constant pressureexpansion |
| Answer» C. throttling | |
| 81. | To convert volumetric analysis to gravimetric analysis, the relative volume of each constituent of the flue gases is |
| A. | divided by its specific weight |
| B. | multiplied by its density |
| C. | multiplied by its molecular weight |
| D. | divided by its molecular weight |
| Answer» C. multiplied by its molecular weight | |
| 82. | a heat engine receives heat at the rate of 1500 kJ/min.& gives an output of 8.2 kW. Its thermal efficiency is equal to |
| A. | 20.5 % |
| B. | 30.2% |
| C. | 32.8% |
| D. | 44.6% |
| Answer» C. 32.8% | |
| 83. | An inventor claims that a new heat cycle will develop 0.4 kW for a heat addition of 32.5 kJ/mm. The temperature of heat source is 1990 K & that of sink is 850K. Is his claim true? |
| A. | true |
| B. | false |
| C. | either of the above |
| D. | unpredictable |
| Answer» B. false | |
| 84. | Consider the following statements: The definition of 1. temperature is due to zeroth law of thermodynamics 2. entropy is due to first law of thermodynamics 3. internal energy is due to second law of thermodynamics 4. reversibility is due to Kelvin-Planck’s ststement of these statements |
| A. | 1,2 & 3 are correct |
| B. | 1,3 & 4 are correct |
| C. | 1 alone is correct |
| D. | 2 alone is correct |
| Answer» C. 1 alone is correct | |
| 85. | A heat engine is supplied with 250 kJ/s of heat at a constant fixed temperature of 227°C. The heat is rejected at 27°C. The cycle is reversible, if the amount of heat rejected is |
| A. | 273 kj/s |
| B. | 200 kj/s |
| C. | 180 kj/s |
| D. | 150 kj/s |
| Answer» D. 150 kj/s | |
| 86. | A Carnot engine receiving heat at 400K has an efficiency of 25%. The C.O.P. of a Carnot refrigerator working between the same temperature limits is |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» C. 3 | |
| 87. | If a heat enine gives an output of 3 kW when the input is 10,000 J/s, then the thermal efficiency of the engine will be |
| A. | 20% |
| B. | 30% |
| C. | 70% |
| D. | 76.7% |
| Answer» B. 30% | |
| 88. | The fundamental unit of enthalpy is |
| A. | mlt ???? |
| B. | ml??t???? |
| C. | ml??t ???? |
| D. | ml??t ???? |
| Answer» C. ml??t ???? | |
| 89. | In a cyclic heat engine operating between a source temperature of 600°C & a sink temperature of 20°C, the least rate of heat rejection per kW net output of the engine is |
| A. | 0.460 kw |
| B. | 0.505 kw |
| C. | 0.588 kw |
| D. | 0.650 kw |
| Answer» B. 0.505 kw | |
| 90. | In a reversible cycle, the source temperature is 227°C & the sink temperature is 27°C. The maximum available work for a heat input of 100 kJ will be |
| A. | 100 kj |
| B. | 60 kj |
| C. | 40 kj |
| D. | 88 kj |
| Answer» C. 40 kj | |
| 91. | A heat engine using lake water at 12° C as source & the surrounding atmosphere at 2°C as sink executes 1080 cycles per min. If the amount of heat drawn per cycle is 57J, then the output of the engine will be |
| A. | 66 w |
| B. | 56 w |
| C. | 46 w |
| D. | 36 w |
| Answer» D. 36 w | |
| 92. | One reversible heat engine operates between 1600 K & T₂ K & another reversible heat engine operates between T₂ K & 400 K. If both the engines have the temperature T₂ must be equal to |
| A. | 100 kj |
| B. | 1200 k |
| C. | 1400 k |
| D. | 800 k |
| Answer» D. 800 k | |
| 93. | An engine receives 15152 J/s of heat & produces 5 KW of power. The efficiency of the engine is |
| A. | 25% |
| B. | 27.5% |
| C. | 30% |
| D. | 33% |
| Answer» A. 25% | |
| 94. | Choose the correct statement |
| A. | pressure, temp. & entropy are extensiveproperties |
| B. | pressure, temp. & entropy are intensiveproperties |
| C. | pressure, volume & temp. are extensive properties |
| D. | volume & entropy are extensive properties |
| Answer» D. volume & entropy are extensive properties | |
| 95. | The second law of thermodynamics defines |
| A. | heat |
| B. | enthalpy |
| C. | internal energy |
| D. | entropy |
| Answer» D. entropy | |
| 96. | Which law of thermodynamics defines entropy |
| A. | first |
| B. | second |
| C. | third |
| D. | zeroeth |
| Answer» B. second | |
| 97. | Which of the following processes is essentially irreversible |
| A. | isothermal |
| B. | adiabatic |
| C. | isentropic |
| D. | thrittling |
| Answer» D. thrittling | |
| 98. | A thermodynamic cycle operates between 400 K. & 290 K. 500 MJ/s of heat is added to the working substance. The power generated is |
| A. | 290 mw |
| B. | 290 mj |
| C. | 137.5 mw |
| D. | 137.5 mj |
| Answer» D. 137.5 mj | |
| 99. | A reversible engine performing as engine has efficiency of 62.5%. If it is reversed to work as refrigerator its COP will be |
| A. | 60% |
| B. | 62.5% |
| C. | 65% |
| D. | 37.5% |
| Answer» C. 65% | |
| 101. | The amount of heat absorbed by a system at lower temperature is | |
| A. | coeff. of performance | |
| B. | efficiency | |
| C. | work supplied | |
| D. | refrigerating effect | |
| Answer» C. work supplied | ||
| 102. | Tds equation is |
| A. | a) tds=cvdt + t |
| B. | .. |
| Answer» A. a) tds=cvdt + t | |
| 103. | In an ideal gas the partial pressure of a component is |
| A. | inversely proportional to the square of the molefraction |
| B. | directly proportional to the mole fraction |
| C. | inversely proportional to the mole fraction |
| D. | equal to the mole fraction |
| Answer» B. directly proportional to the mole fraction | |
| 104. | The value of the univesal gas constant is |
| A. | 0.314 j/kg k |
| B. | 83.14 kj/kg k |
| C. | 848 kj/kg k |
| D. | 8.314 kj/kg k |
| Answer» D. 8.314 kj/kg k | |
| 105. | Choose the correct answer |
| A. | a perfect gas does not obey the law pv=rt |
| B. | a perfect gas obeys the law pv=rt & has constant specific heat |
| C. | a perfect gas obeys the law pv=rt but have variable specific heat capacities |
| D. | all of the above |
| Answer» B. a perfect gas obeys the law pv=rt & has constant specific heat | |
| 106. | Boyle’s law states that, when tempearture is constant, the volume of a given mass of a perfect gas |
| A. | varies directly as the absolute pressure |
| B. | varies inversely as the absolute pressure |
| C. | varies as square of the absolute pressue |
| D. | does not vary with the absolute pressure |
| Answer» B. varies inversely as the absolute pressure | |
| 107. | Charle’s law states that if any gas is heated at constant pressure, its volume |
| A. | changes directly as it absolute temperature |
| B. | changes inversely as its absolute temperature |
| C. | changes as square of the absolute temperature |
| D. | does not change with absolute temperature |
| Answer» A. changes directly as it absolute temperature | |
| 108. | The equation of state of an ideal gas is a relationship between the variables: |
| A. | pressure & volume |
| B. | pressure & temperature |
| C. | pressure, volume & temperature |
| D. | none of the above |
| Answer» C. pressure, volume & temperature | |
| 109. | Joule’s law states that the specific internal energy of a gas depends only on |
| A. | the pressure of the gas |
| B. | the volume of the gas |
| C. | the temperature of the gas |
| D. | none of the above |
| Answer» C. the temperature of the gas | |
| 110. | ………. Law states that equal volume of all gases, at the same temperature & pressure, contains equal number of molecules |
| A. | boyle’s |
| B. | gay-lussac |
| C. | avogadro |
| D. | charle’s |
| Answer» C. avogadro | |
| 111. | The change of entropy is considered to be ……… when heat is absorbed by the gas |
| A. | positive |
| B. | negative |
| C. | zero |
| D. | none of the above |
| Answer» A. positive | |
| 112. | ………. Is one in which neither any heat enters nor leaves the system |
| A. | isochoric process |
| B. | isobaric process |
| C. | isentropic process |
| D. | isothermal process |
| Answer» C. isentropic process | |
| 113. | Entropy of the universe |
| A. | tends to zero |
| B. | tends to a minimum |
| C. | tends to a maximum |
| D. | none of the above |
| Answer» C. tends to a maximum | |
| 114. | A gas can never be liquid |
| A. | above criticaltemperature |
| B. | when it is diatomic |
| C. | when it is impure |
| D. | above roomtemperature |
| Answer» A. above criticaltemperature | |
| 115. | Which of the following remains constant during an adiabatic expansion |
| A. | entropy |
| B. | temperature |
| C. | internal energy |
| D. | none of the above |
| Answer» A. entropy | |
| 116. | In which of the following processes the change in internal energy of a gas is equal to the work done |
| A. | adiabatic process |
| B. | isothermal process |
| C. | constant volume process |
| D. | constant pressure process |
| Answer» A. adiabatic process | |
| 117. | The specific heat of a gas is a function of |
| A. | temperature only |
| B. | temperature & pressure |
| C. | temperature & entropy |
| D. | temperature, pressure& entropy |
| Answer» A. temperature only | |
| 118. | In a Carnot cycle which of the following processez must be carried out at extremely slow speed? |
| A. | isothermal compression |
| B. | adiabatic expansion |
| C. | adiabatic compression |
| D. | none of the above |
| Answer» A. isothermal compression | |
| 119. | In the case of real gases, cp will be equal to cv |
| A. | at absolute zero |
| B. | at triple point |
| C. | at critical temperature |
| D. | above criticaltempeature |
| Answer» A. at absolute zero | |
| 120. | The physical properties of a perfect gas are controlled by which of the following variables? |
| A. | volume |
| B. | temperature |
| C. | pressure |
| D. | all of the above |
| Answer» D. all of the above | |
| 121. | Universal gas constant is defined as equal to the product of the molecular weight of the gas & |
| A. | gas constant |
| B. | specific heat at constant volume |
| C. | specific heat a constant pressure |
| D. | ratio of two specific heats |
| Answer» A. gas constant | |
| 122. | All engineering process, strictly speaking are |
| A. | reversible cycle |
| B. | irreversible |
| C. | quasti-static |
| D. | thermodynamically inequillibrium |
| Answer» D. thermodynamically inequillibrium | |
| 123. | Isothermal, isobaric, isochoric & adiabatic processes, under ideal conditions, are …. Processes |
| A. | thermodynamic |
| B. | stable |
| C. | dynamic |
| D. | quasi-static |
| Answer» D. quasi-static | |
| 124. | Change of entropy depends upon which of the following? |
| A. | change of heat |
| B. | change of specific heats |
| C. | change of pressure &volume |
| D. | none of the above |
| Answer» A. change of heat | |
| 126. | During a throttling process |
| A. | exchange of heat doesnot take place |
| B. | expandingsteam does nowork |
| C. | internal energy of steamdoes not change |
| D. | all of the above |
| Answer» D. all of the above | |
| 127. | Under which of the following conditions all gases behave ideally? |
| A. | high pressure conditions |
| B. | law pressure conditions |
| C. | vaccum conditions |
| D. | all of the aboveconditions |
| Answer» B. law pressure conditions | |
| 128. | ……….. Is the unit of entropy |
| A. | j/kg |
| B. | j/kg k |
| C. | j/k |
| D. | j/kgs |
| Answer» B. j/kg k | |
| 129. | Internal energy & enthalpy of an ideal gas are functions of |
| A. | pressure only |
| B. | temperature only |
| C. | specific volume only |
| D. | temperature & pressure |
| Answer» B. temperature only | |
| 130. | When two gases suddenly mix up with each other then resultant entropy of the system will |
| A. | remain unaltered |
| B. | decrease |
| C. | increase |
| D. | becomes zero |
| Answer» C. increase | |
| 131. | On which of the following factors does air standard efficiency of a diesel cycle depend? |
| A. | adiabatic compression ratio |
| B. | ratio of specific heats |
| C. | cut-off ratio |
| D. | all of the above |
| Answer» D. all of the above | |
| 132. | Regarding enthalpy which of the following statements is incorrect? |
| A. | it is the function of specific heat at constantvolume |
| B. | it is the extensive property of the system |
| C. | it is the sum of internal energy & the pressurevolume product |
| D. | it is the same as heat transfer during constantpressure process |
| Answer» A. it is the function of specific heat at constantvolume | |
| 133. | Which of the following processes is reversible process? |
| A. | throttling |
| B. | adiabatic |
| C. | isothermal |
| D. | none of the above |
| Answer» A. throttling | |
| 134. | Which of the following processes are reversible processes? |
| A. | isothermal & adiabatic |
| B. | constant volume &constant pressure |
| C. | hyperbolic & pv?= constant |
| D. | none of the above |
| Answer» A. isothermal & adiabatic | |
| 135. | For ……. The internal energy & enthalpy are the functions of temperature only |
| A. | perfect gas |
| B. | water in pipes surrounded by steam |
| C. | saturated steam |
| D. | superheated steam |
| Answer» A. perfect gas | |
| 136. | The index of compression n tends to reach ?(ratio of specific heats) |
| A. | when process is isothermal |
| B. | when process is isentropic |
| C. | when process is isentropic & specific heat does not change with temperature |
| D. | when flow is uniform & steady |
| Answer» C. when process is isentropic & specific heat does not change with temperature | |
| 137. | In the reversible polytropic process the value of exponent n varies between |
| A. | 0.2 to 1 |
| B. | 1.0 to 1.2 |
| C. | 1.2 to 1.4 |
| D. | 1.4 to 2.0 |
| Answer» C. 1.2 to 1.4 | |
| 138. | An ideal gas as compared to a real gas at very high pressure occupies |
| A. | same volume |
| B. | less volume |
| C. | more volume |
| D. | all of the above |
| Answer» C. more volume | |
| 139. | Adiabatic & isothermal processes are identical at |
| A. | absolute zerotemperature |
| B. | below 0°c temperature |
| C. | saturation temperature |
| D. | critical temperature |
| Answer» A. absolute zerotemperature | |
| 140. | In polytropic process pv?=C the value of exponent n=±? is indicative of |
| A. | isobaric process |
| B. | isentropic process |
| C. | isochoric process |
| D. | throttling process |
| Answer» C. isochoric process | |
| 141. | Entropy in statistical thermodynamics is defined as |
| A. | a universal property |
| B. | reversible heat transfer |
| C. | degree of randomness |
| D. | measure of reversibilityof a system |
| Answer» C. degree of randomness | |
| 142. | A mixture of gases expands from 0.03 m³ to 0.06 m³ at a constant pressure of 1 Mpa & absorbs 84 kJ of heat during the process. The change in internal energy of the mixture is |
| A. | 30 kj |
| B. | 54 kj |
| C. | 84 kj |
| D. | 114 kj |
| Answer» B. 54 kj | |
| 143. | Increase in entropy of a system represents |
| A. | increase in availability ofenergy |
| B. | increase in temperature |
| C. | decrease in pressure |
| D. | degradation of energy |
| Answer» D. degradation of energy | |
| 144. | Which one of the following pairs best expresses a relationship similar to that expressed in the pair ‘pressure-volume’ for a thermodynamic system undergoing a process? |
| A. | enthalpy-entropy |
| B. | pressure-enthalpy |
| C. | pressure-temperature |
| D. | temperature-entropy |
| Answer» D. temperature-entropy | |
| 145. | Variations of pressure & volume at constant temperature are correlated through |
| A. | charle’s law |
| B. | boyle’s law |
| C. | gas law |
| D. | gay lussac’s law |
| Answer» B. boyle’s law | |
| 146. | The relationship between pressure & volume is expressed as pv?=const. Select wrong statement |
| A. | expansion with n=0 is a constant pressure process |
| B. | expansion with n=? is an adiabatic process |
| C. | expansion with n=? is not possible |
| D. | expansion at constant temperature has n=1 |
| Answer» C. expansion with n=? is not possible | |
| 147. | A gas expands from initial condition of (p1, v1, T1) to final condition (p2, v1, T2), then according to Charle’s law: |
| A. | p1t1=p2t2 |
| B. | p1p2 = t1t2 |
| C. | p1+ t2 = p2 + t1 |
| D. | p1t2 = p2t1 |
| Answer» D. p1t2 = p2t1 | |
| 148. | Air expands from initial condition of p1, v1 to final condition of 1/2 p1, 2v1. Choose the correct statement |
| A. | no work is performed during expansion |
| B. | expansion is isothermal |
| C. | expansion is polytropic with n= 1.2 |
| D. | expansion is adiabatic |
| Answer» C. expansion is polytropic with n= 1.2 | |
| 149. | Air with initial condition of p1, v1 expands to final condition of p1/2, 3v1. The process is |
| A. | hyperbolic |
| B. | adiabatic |
| C. | polytropic with n > 1 |
| D. | polytropic with n < 1 |
| Answer» A. hyperbolic | |
| 151. | During a polytropic expansion 25% of heat is converted into work while temperature of gas rises by 30 K, the specific heat of gas at constant volume is | |
| A. | 10% w | |
| B. | 12 % w | |
| C. | 15% w | |
| D. | 20% w | |
| Answer» B. 12 % w | ||
| 152. | During a constant pressure expansion of a gas 33.3 % heat is converted into work while the temperature rises by 20K. The specific heat of gas at constant pressure is |
| A. | 10% w |
| B. | 12 % w |
| C. | 15% w |
| D. | 20% w |
| Answer» C. 15% w | |
| 153. | During an adiabatic compression when temperature increase by 100% the pressure increases by 1000%. The ratio of specific heats, ? is |
| A. | 1.3 |
| B. | 1.35 |
| C. | 1.4 |
| D. | 1.45 |
| Answer» C. 1.4 | |
| 154. | In an constant pressure heating certain fraction of heat supplied is converted into work. If ?=1.4 this fraction is |
| A. | 0.25 |
| B. | 0.286 |
| C. | 0.3 |
| D. | 0.327 |
| Answer» D. 0.327 | |
| 155. | The area under the curve on temperature entropy diagram represents |
| A. | work done during the process |
| B. | heat exchanged during the process |
| C. | change in internal energy during the process |
| D. | change in entropy during the process |
| Answer» B. heat exchanged during the process | |
| 156. | The change in entropy is zero during |
| A. | hyperbolic process |
| B. | constant pressureprocess |
| C. | adiabatic processes |
| D. | polytropic process |
| Answer» C. adiabatic processes | |
| 157. | Choose incorrect statement |
| A. | isentropic process is adiabatic |
| B. | adiabatic process has no heat exchange |
| C. | hyperbolic process is isothermal |
| D. | no work is done in constant pressure process |
| Answer» D. no work is done in constant pressure process | |
| 158. | Choose the correct statement |
| A. | there is no change of entropy in an adiabatic expansion |
| B. | entropy is an extensive property of gas derived from first law of thermodynamics |
| C. | the area under the curve in a temp.-entropy diagram gives the change of entropy |
| D. | the change of entropy during a constant pressure process is always negative |
| Answer» B. entropy is an extensive property of gas derived from first law of thermodynamics | |
| 159. | 1.6 Kg of air is expanded at constant pressure from 100°C to 0°C resulting in entropy change of – 2.0 J/K 3.2 Kg of air is cooled at constant volume from 100°C to 0°C with a change in entropy of -3.0 J/K. The ratio Cp/ Cv is |
| A. | 1.333 |
| B. | 1.366 |
| C. | 1.4 |
| D. | 1.43 |
| Answer» C. 1.4 | |
| 160. | Entropy at absolute zero temperature is zero for a |
| A. | perfect gas |
| B. | perfect substance |
| C. | perfect crystal |
| D. | glass |
| Answer» C. perfect crystal | |
| 161. | The third law of thermodynamics |
| A. | defines entropy |
| B. | provides a base from which entropy is measured |
| C. | defines change of entropy |
| D. | gives availability of heat for conversion into work |
| Answer» D. gives availability of heat for conversion into work | |
| 162. | Entropy is called the property of a system because |
| A. | it has same value at any two equilibrium states |
| B. | it depends upon the process path |
| C. | it has a unique value at each equilibrium state |
| D. | it does not change between two equilibriumstates |
| Answer» A. it has same value at any two equilibrium states | |
| 163. | Entropy of mixture of two gases after sudden mixing is |
| A. | greater than |
| B. | less than its inputtemperature |
| C. | same as sum of entropy ofindividual gases |
| D. | unpredictable |
| Answer» A. greater than | |
| 164. | If a substance goes though a cycle of changes returning back to original state, the change in entropy is |
| A. | positive |
| B. | negative |
| C. | zero |
| D. | positive or negative depending upon originalstate |
| Answer» B. negative | |
| 165. | A sequence of operations which a gas undergoes in such a way that final state is same as original state, mahe a |
| A. | reversible cycle |
| B. | irreversible cycle |
| C. | thermal cycle |
| D. | thermodynamic cycle |
| Answer» D. thermodynamic cycle | |
| 166. | In a reversible process |
| A. | heat transfer takes place over finite temperaturedifference |
| B. | heat transfer takes place over infinitesimaltemperature difference |
| C. | heat transfer takes place from surrounding to thesystem |
| D. | heat transfer takes place from the system tothe surrounding |
| Answer» C. heat transfer takes place from surrounding to thesystem | |
| 167. | Which of the following processes is very close to reversible |
| A. | lifting of a body above the ground |
| B. | compression of a gas in the cylinder against a piston |
| C. | flow of a fluid in a pipe |
| D. | motion of a boat in water |
| Answer» C. flow of a fluid in a pipe | |
| 168. | A perfect gas having p1= 0.1 M/mm², v1=0.18 m³, T1=20°C is compressed to 1/10 of volume in an isothermal process. The change in entropy is |
| A. | -141.45 j/k |
| B. | 141.45 j/k |
| C. | -41446.23 j/k |
| D. | 0 |
| Answer» B. 141.45 j/k | |
| 169. | The enthalpy of a system |
| A. | i= internal energy + pv |
| B. | i= internal energy + pdv |
| C. | i= internal energy + vdp |
| D. | i= change in internalenergy + pv |
| Answer» B. i= internal energy + pdv | |
| 170. | During a polytropic expansion work obtained is 1.8 times the heat transferred. If ?=1.4, n will be |
| A. | 1.2 |
| B. | 1.19 |
| C. | 1.178 |
| D. | 1.155 |
| Answer» D. 1.155 | |
| 171. | Which statement is wrong for throttling expansion |
| A. | pressure drop = 0 |
| B. | change in enthalpy = 0 |
| C. | work done = 0 |
| D. | change in internalenergy = 0 |
| Answer» C. work done = 0 | |
| 172. | Which statement is wrong for adiabatic expansion |
| A. | h = 0 |
| B. | w = 0 |
| C. | ds = 0 |
| D. | w+e = 0 |
| Answer» D. w+e = 0 | |
| 173. | Maximum amount of work that can be converted into heat in any process |
| A. | depends upon initial & final temperature |
| B. | depends upon how much work is lost in friction |
| C. | is 50% |
| D. | is 100% |
| Answer» B. depends upon how much work is lost in friction | |
| 174. | The universal gas constant will be equal to difference between specific heats at constant pressure & constant volume for |
| A. | 1 kg mass of gas |
| B. | 1 molecule of gas |
| C. | 1 kg molecule of gas |
| D. | any mass of gas |
| Answer» C. 1 kg molecule of gas | |
| 176. | The latent heat of vapouristation at critical point is |
| A. | less than zero |
| B. | greater than zero |
| C. | equal to zero |
| D. | none of the above |
| Answer» C. equal to zero | |
| 177. | Choose the correct answer |
| A. | critical point involves equilibrium of solid & vapour phases |
| B. | critical point involves equilibrium of solid & liquid phases |
| C. | critical point involves equilibrium of solid, liquid & vapour phases |
| D. | triple point involves equilibrium of solid, liquid & vapour phases |
| Answer» D. triple point involves equilibrium of solid, liquid & vapour phases | |
| 178. | With the increase in pressure |
| A. | boiling point of water increases & enthalpy of evaporation increases |
| B. | boiling point of water increases & enthalpy of evaporation decreases |
| C. | boiling point of water decreases & enthalpy of evaporation increases |
| Answer» B. boiling point of water increases & enthalpy of evaporation decreases | |
| 179. | With increase in pressure |
| A. | enthalpy of dry saturated steam increases |
| B. | enthalpy of dry saturated steam decreases |
| C. | enthalpy of dry saturated steam remains same |
| D. | enthalpy of dry saturated steam first increases & thendecreases |
| Answer» B. enthalpy of dry saturated steam decreases | |
| 180. | Dryness fraction of steam is defined as |
| A. | mass of water vapour in suspension/(mass of water vapour in suspension+mass of dry steam) |
| B. | mass of dry steam/mass of water vapour in suspension |
| C. | mass of dry steam/(mass of dry steam+mass of water vapour in suspension) |
| D. | mass of water vapour in suspension/mass of dry steam |
| Answer» C. mass of dry steam/(mass of dry steam+mass of water vapour in suspension) | |
| 181. | Only throttling calorimeter is used for measuring |
| A. | very low dryness fraction upto 0.7 |
| B. | very high dryness fraction upto 0.98 |
| C. | dryness fraction of only low pressure steam |
| D. | dryness fraction ofonly high pressure steam |
| Answer» B. very high dryness fraction upto 0.98 | |
| 182. | Rankine cycle efficiency of a good steam power plant may be in the range of |
| A. | 15 to 20% |
| B. | 35 to 45% |
| C. | 70 to 80% |
| D. | 90 to 95% |
| Answer» B. 35 to 45% | |
| 183. | Rankine cycle operating on low pressure limit of p1 & high pressure limit p2 |
| A. | has higher thermal efficiency than the carnot cycle operating between same pressure limits |
| B. | has lower thermal efficiency than carnot cycle operating between same pressurelimits |
| C. | has same thermal efficiency than carnot cycle operating between same pressure limits |
| D. | may be more or less depending upon the magnitudes of p1 & p2 |
| Answer» A. has higher thermal efficiency than the carnot cycle operating between same pressure limits | |
| 184. | Rankine cycle comprises of |
| A. | two isetropic processes & two constant volume processes |
| B. | two isentropic processes & two constant pressureprocesses |
| C. | two isothermal processes & two constant pressureprocesses |
| D. | none of the above |
| Answer» B. two isentropic processes & two constant pressureprocesses | |
| 185. | In Rankine cycle the work output from the turbine is given by |
| A. | change of internal energy between inlet & outlet |
| B. | change of enthalpy between inlet & outlet |
| C. | change of entropy between inlet & outlet |
| D. | change of temperature between inlet & outlet |
| Answer» B. change of enthalpy between inlet & outlet | |
| 186. | The maximum percentage gain in Regenerative feed heating cycle thermal effciency |
| A. | increases with number of feed heaters increasing |
| B. | decreases with number of feed heaters increasing |
| C. | remains same unaffected by number of feed heaters |
| D. | none of the above |
| Answer» A. increases with number of feed heaters increasing | |
| 187. | In an unsaturated air the state of a vapour is |
| A. | wet |
| B. | superheated |
| C. | saturated |
| D. | unsaturated |
| Answer» B. superheated | |
| 188. | The efficiency of the Carnot cycle may be increased by |
| A. | decreasing the lowest temperature |
| B. | increasing the lowest temperature |
| C. | increasing the highest temperature |
| D. | both a & c |
| Answer» D. both a & c | |
| 189. | Most of the fossil fuel based power plants operate on |
| A. | rankine cycle |
| B. | brayton cycle |
| C. | carnot cycle |
| D. | either rankine or brayton cycle |
| Answer» D. either rankine or brayton cycle | |
| 190. | Efficiency of Rankine cycle is function of |
| A. | highest temperature of cycle |
| B. | lowest temperature of cycle |
| C. | both highest & lowest temperature of the cycle |
| D. | none of the above |
| Answer» C. both highest & lowest temperature of the cycle | |
| 191. | Essential parts of a power plant operating on a Rankine cycle are |
| A. | engine or turbine |
| B. | engine or turbine & conderser |
| C. | gine or turbine, condenser, pump &boiler |
| D. | engine or turbine & boiler |
| Answer» C. gine or turbine, condenser, pump &boiler | |
| 192. | Correlate the following statements i) the volume of water into which steam is condensed in condenser is very much smaller than the volume of steam before condensation ii) the net work of a Rankine cycle is heat supplied in boiler – heat rejected to condenser – pump work |
| A. | both i) & ii) are correct, i) is the correct reason for ii) |
| B. | i) & ii) are correct, ii) is the correct interpretation if i) |
| C. | both i) & ii) are not correct |
| D. | both i) & ii) are independently correct |
| Answer» D. both i) & ii) are independently correct | |
| 193. | By reducing the condenser pressure in Rankine power plant |
| A. | heat supplied increases & work of cycle decreases |
| B. | work of cycle & moisture content of steam in l.p side ofturbine increase |
| C. | heat supplied & efficiency of cycle increase |
| D. | work of cycle increases but heat supplied decreases |
| Answer» B. work of cycle & moisture content of steam in l.p side ofturbine increase | |
| 194. | Correlate the following statements i) by reducing the condenser pressure in a Rankine cycle work output is increased ii) increased proportion of moisture in turbine is undesirable because water particles erode the blades |
| A. | both i) & ii) are independently true |
| B. | both i) & ii) are not true |
| C. | i) is true but ii) is not |
| D. | ii) is true but i) is not |
| Answer» A. both i) & ii) are independently true | |
| 195. | Turbine blade efficiency reduces in a Rankine cycle if |
| A. | heat supply in boiler increases |
| B. | heat supply in boiler decreases |
| C. | condenser pressure decreases |
| D. | condenser pressure increases |
| Answer» C. condenser pressure decreases | |
| 196. | A Rankine cycle with reheat |
| A. | increases heat supply but reduces work |
| B. | increases efficiency but reduces work |
| C. | increases moisture content in l.p side of turbine but increases work |
| D. | increases efficiency but reduces moisture content in l.p side of turbine |
| Answer» D. increases efficiency but reduces moisture content in l.p side of turbine | |
| 197. | The main advantage of a Reheat Rankine cycle is |
| A. | reduced moisture content in l.p side of turbine |
| B. | increased efficiency |
| C. | increased work of turbine |
| D. | reduced load on condenser |
| Answer» A. reduced moisture content in l.p side of turbine | |
| 198. | A Reheat Rankine cycle |
| A. | reduces total heat produced in boiler |
| B. | increases total heat produced in boiler |
| C. | increases volume of steam produced in boiler |
| D. | reduces volume of steam produced inboiler |
| Answer» B. increases total heat produced in boiler | |
| 199. | Choose the wrong statement |
| A. | volume of steam passing through h.p & l.p sides of the turbine is same in simple rankine cycle |
| B. | volume of steam passing through l.p side of turbine & condenser is same in regenerative rankine cycle |
| C. | volume of steam passing through h.p side of the turbine & condenser is same in regenerative rankinecycle |
| D. | volume of steam passing through h.p side of the turbine & condenser is same in reheat rankine cycle |
| Answer» C. volume of steam passing through h.p side of the turbine & condenser is same in regenerative rankinecycle | |
| 201. | Considerfollowing options for a simple Rankine cycle i) increasing pressure at exist of turbine ii) increasing average temperature of heat addition iii) decreasing pressure at exit of turbine iv) superheating of steam v) decreasing pressure during superheating. Which combination of above will increase Rankine efficiency? |
| A. | i), ii) & iv) |
| B. | i), ii) & v) |
| C. | iii), iv) & v) |
| D. | ii), iii) & iv) |
| Answer» D. ii), iii) & iv) | |
| 202. | Higher dryness fraction of steam at turbine exit in a Rankine cycle |
| A. | will increase cycle efficiency |
| B. | will increase turbine work |
| C. | will protect turbine blading |
| D. | will reduce pump work |
| Answer» C. will protect turbine blading | |
| 203. | The main purpose of reheat Rankine cycle is |
| A. | to reduce moisture in steam & thus to protect turbine blading |
| B. | to obtain significant gain in efficiency |
| C. | to obtain significant gain in net work |
| D. | to reduce heat supplied & yet maintain turbine work |
| Answer» D. to reduce heat supplied & yet maintain turbine work | |
| 204. | The temperature of feed water can be increased in following two ways in a regenerative Rankine cycle i) by passing feed water around turbine casing in direction opposite to flow of steam ii) by bleeding certain portion of steam at the end of h.p expansion & mixing with condensate to make feed water at the temperature of boiler |
| A. | i) is preferred over ii) for higher efficiency |
| B. | ii) is preferred over i) for reduced moisture content of steam in l.p side |
| C. | only i) is implemented in actual practice |
| D. | by preferring ii) overi) significant gain in efficiency results |
| Answer» B. ii) is preferred over i) for reduced moisture content of steam in l.p side | |
| 205. | In a steam power plant which cycle requires two or more feed pumps |
| A. | regenerative rankine cycle |
| B. | reheat rankine cycle |
| C. | simple rankine cycle |
| D. | idealized regenerative rankine cycle |
| Answer» A. regenerative rankine cycle | |
| 206. | In a regenerative Rankine cycle as compared to simple Rankine cycle |
| A. | the pump work is smaller |
| B. | the addition of heat is smaller |
| C. | the superheat is to lesser extent |
| D. | the heat rejected in condenser is smaller |
| Answer» D. the heat rejected in condenser is smaller | |
| 207. | A Rankine cycle is less efficient than Carnot cycle because |
| A. | the working fluid is steam |
| B. | heat is not added athighest temperature of cycle |
| C. | condensation processis extended into liquid phase |
| D. | superheating occurs at constant pressure |
| Answer» B. heat is not added athighest temperature of cycle | |
| 208. | A regenerative Rankine cycle may approach efficiency of a Carnot cycle between same temperature by |
| A. | reducing heat to condenser |
| B. | reducing volume of steam passed into condenser |
| C. | increasing turbine work |
| D. | adding heat a highest temp. |
| Answer» D. adding heat a highest temp. | |
| 209. | Average temp.at which heat is supplied is increased in |
| A. | simple rankine cycle |
| B. | reheat rankine cycle |
| C. | regenerative rankine cycle |
| D. | modified rankine cycle |
| Answer» C. regenerative rankine cycle | |
| 210. | A power cycle using steam as working fluid consist of i) constant pressure heat addition ii)adiabatic expansion iii) constant pressure heat rejection & iv) adiabatic compression. The cycle is |
| A. | simple rankine cycle |
| B. | modified rankine cycle |
| C. | carnot cycle |
| D. | regenerative rankine cycle |
| Answer» C. carnot cycle | |
| 211. | Steam enters the turbine at 5.44 bar with dryness fraction of 0.9 & is expanded adiabatically to a pressure of 0.68 bar. It will enter the condenser with a quality very close to |
| A. | 0.79 |
| B. | 0.815 |
| C. | 0.84 |
| D. | 0.86 |
| Answer» B. 0.815 | |
| 212. | A Rankine cycle has efficiency of 19.4%. The steam enters the turbine with enthalpy of 32.85 kJ/Kg while heat of water entering the boiler is 423.6 kJ/Kg.the work of the turbine is 560 kJ/ Kg. the pump work is |
| A. | 3.5 kj/kg |
| B. | 5 kj/kg |
| C. | 6.5 kj/kg |
| D. | 7 kj/kg |
| Answer» B. 5 kj/kg | |
| 213. | A steam power plant working on Rankine cycle produces steam in the boiler at a rate of 100 kg/s with enthalpy of 3280 kJ/kg from water whose total heat content is 420 kJ/kg. The plant has Rankine efficiency of 24.65 while pump requires 5 kJ/kg of work. The turbine generates power of |
| A. | 71 mw |
| B. | 71.5 mw |
| C. | 72 mw |
| D. | 72.5 mw |
| Answer» A. 71 mw | |
| 214. | In a simple Rankine cycle steam was expanded from 100 bar & 380°C to 1 bar 0.8 dry state. The pump motor consumes 10 kJ/kg of energy. The efficiency of cycle is |
| A. | 31% |
| B. | 34% |
| C. | 29.8% |
| D. | 30.6% |
| Answer» D. 30.6% | |
| 215. | In a reheat Rankine cycle steam with enthalpy of 3300 kJ/kg is expanded in h.p turbine to a state where enthalpy is 2650 kJ/kg. The steam is further expnaded from a state where enthalpy is 2950 kJ/kg to enthalpy of 2525 kJ/kg & latent heat of 2201 kJ.kg. The work of the cycle & amount of reheat respectively are |
| A. | 1075 kj/kg,300 kj.kg |
| B. | 1399 kj/kg, 300 kj/kg |
| C. | 1075 kj/kg, 324 kj/kg |
| D. | 1399 kj/kg, 324 kj/kg |
| Answer» A. 1075 kj/kg,300 kj.kg | |
| 216. | In above question the heat supplied & efficiency respectively are |
| A. | 3276 kj/kg, 42.7% |
| B. | 2976 kj/kg, 36.12% |
| C. | 300 kj/kg, 32.6% |
| D. | 330 kj/kg, 42.4% |
| Answer» B. 2976 kj/kg, 36.12% | |
| 217. | Due to which of the following reasons the Carnot cycle cannot be realised in actual practice? |
| A. | high volume ratios in the cylinder |
| B. | very high pressure developed in the cylinder |
| C. | both a & b |
| D. | none of the above |
| Answer» C. both a & b | |
| 218. | The flow through turbine on a Mollier chart is represented by |
| A. | vertical line |
| B. | horizontal line |
| C. | curved line convex up |
| D. | curved line convex down |
| Answer» A. vertical line | |
| 219. | The latent enthalpy of vapourisation at critical point is |
| A. | zero |
| B. | minimum |
| C. | maximum |
| D. | none of the above |
| Answer» A. zero | |
| 220. | Above critical point, a substance exists as |
| A. | vapour |
| B. | liquid |
| C. | gas |
| D. | supersaturated fluid |
| Answer» D. supersaturated fluid | |
| 221. | Triple point of a pure substance is a point at which |
| A. | solid & vapour exist together |
| B. | solid & liquid exist together |
| C. | liquid & vapour exist together |
| D. | solid, liquid & vapour phases existtogether |
| Answer» D. solid, liquid & vapour phases existtogether | |
| 222. | Which of the following cycles is used in thermal power plants? |
| A. | brayton |
| B. | carnot |
| C. | ericsson |
| D. | rankine |
| Answer» D. rankine | |
| 223. | In a Carnot engine, when the working substance rejects its heat to sink, the temperature of sink |
| A. | remains same |
| B. | decrease |
| C. | increases |
| D. | becomes 0??k |
| Answer» A. remains same | |
| 224. | Which of the following is used as a working substance for a Carnot cycle? |
| A. | ideal gas |
| B. | real gas |
| C. | steam |
| D. | atmospheric air |
| Answer» A. ideal gas | |
| 226. | The gas laws can be used with minimum error is case of | |
| A. | wet steam | |
| B. | dry steam | |
| C. | saturated steam | |
| D. | superheated steam | |
| Answer» D. superheated steam | ||
| 227. | Mathematically a pure substance can be written as |
| A. | p=f(t,v) |
| B. | v= f(p,t) |
| C. | t=f(p,v) |
| D. | any of the above |
| Answer» D. any of the above | |
| 228. | A Carnot cycle operates between source & sink temperatures of 250°C & – 15°C. If the system receives 90kJ from the source then the net work transfer equals |
| A. | 30.5 kj |
| B. | 35.65 kj |
| C. | 45.54 kj |
| D. | 65.54 kj |
| Answer» C. 45.54 kj | |
| 229. | Consider the following statements regarding superheating in Rankine Cycles 1. It reduces the specific steam consumption 2. It increases the dryness fraction of steam at the exhaust for the same value of condenser pressure 3. It reduces the cycle efficiency Of the these statements |
| A. | 1 & 2 are correct |
| B. | 2 & 3 are correct |
| C. | 1 & 3 are correct |
| D. | 1, 2 & 3 are correct |
| Answer» A. 1 & 2 are correct | |
| 230. | Energy is a |
| A. | point function |
| B. | property of the system |
| C. | extensive property |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 231. | The specific energy, e=E/m is an extensive property. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 232. | (m*V*V)/2 gives the |
| A. | macroscopic kinetic energy |
| B. | microscopic kinetic energy |
| C. | macroscopic potential energy |
| D. | microscopic potential energy |
| Answer» A. macroscopic kinetic energy | |
| 233. | (m*g*z) gives the |
| A. | macroscopic kinetic energy |
| B. | microscopic kinetic energy |
| C. | macroscopic potential energy |
| D. | microscopic potential energy |
| Answer» C. macroscopic potential energy | |
| 234. | Which of the following types of energy can be present in molecules? |
| A. | translational and rotational kinetic energy |
| B. | electronic energy and vibrational energy |
| C. | chemical energy and nuclear energy |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 235. | The total internal energy of the system is given by |
| A. | u=n/ɛ |
| B. | u=nɛ |
| C. | u=ɛ/n |
| D. | none of the mentioned |
| Answer» B. u=nɛ | |
| 236. | In an ideal gas there are no intermolecular forces of attraction and repulsion, and the internal energy is a function of temperature only. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 237. | Which of the following is true in regard to the energy of an isolated system? |
| A. | dq≠0 |
| B. | dw≠0 |
| C. | e=constant |
| D. | all of the mentioned |
| Answer» C. e=constant | |
| 238. | A perpetual motion machine of first kind |
| A. | is a fictitious machine |
| B. | can supply mechanical work without dissipating energy |
| C. | violates first law |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 239. | The limitation of the first law is |
| A. | does not indicate the possibility of a spontaneous process proceeding in a definite direction |
| B. | it assigns a quality to different forms of energy |
| C. | indicates the direction of any spontaneous process |
| D. | none of the mentioned |
| Answer» A. does not indicate the possibility of a spontaneous process proceeding in a definite direction | |
| 240. | Integral of dQ/T is independent of reversible path connecting between two points. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 241. | Integral of dQ/T of a reversible path is given by |
| A. | si-sf |
| B. | sf-si |
| C. | si+sf |
| D. | -si-sf |
| Answer» B. sf-si | |
| 242. | Entropy is a |
| A. | path function, intensive property |
| B. | path function, extensive property |
| C. | point function, intensive property |
| D. | point function, extensive property |
| Answer» D. point function, extensive property | |
| 243. | Specific entropy is given by( where m is the mass) |
| A. | sm |
| B. | m/s |
| C. | s/m |
| D. | none of the mentioned |
| Answer» C. s/m | |
| 244. | For any process which is undergone by a system |
| A. | dq/t>=ds |
| B. | dq/t<=ds |
| C. | dq/t≠ds |
| D. | none of the mentioned |
| Answer» B. dq/t<=ds | |
| 245. | For an irreversible process, |
| A. | ds=dq/t |
| B. | ds>dq/t |
| C. | ds<dq/t |
| D. | none of the mentioned |
| Answer» B. ds>dq/t | |
| 246. | For two different paths between same two points, entropy change is |
| A. | depends on path taken |
| B. | different |
| C. | same |
| D. | none of the mentioned |
| Answer» C. same | |
| 247. | For the general case, we can write |
| A. | s2-s1<=dq/t for a path |
| B. | s2-s1>=dq/t for a path |
| C. | s2-s1≠dq/t for a path |
| D. | none of the mentioned |
| Answer» B. s2-s1>=dq/t for a path | |
| 248. | A reversible process is performed in such a way that |
| A. | at the conclusion of process, both system and surroundings can be restored to their initial states without producing any change |
| B. | it should not leave any trace to show that the process had ever occurred |
| C. | it is carried out infinitely slowly |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 249. | A reversible process coincides with a quasi-static process. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 251. | All actual heat transfer processes are |
| A. | irreversible |
| B. | take place through a finite temperature difference |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 252. | Free expansion is irreversible. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 253. | Which of the following can be a cause of irreversibility? |
| A. | friction, viscosity |
| B. | inelasticity |
| C. | electrical resistance, magnetic hysteresis |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 254. | The continual motion of a movable device in the complete absence of friction is known as |
| A. | pmm2 |
| B. | pmm3 |
| C. | pmm1 |
| D. | pmm0 |
| Answer» B. pmm3 | |
| 255. | The friction present in moving devices makes a process reversible. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 256. | Which of the following is irreversible? |
| A. | stirring work |
| B. | friction work in moving devices |
| C. | current flowing through a wire |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 257. | A process will be reversible if it has |
| A. | no dissipative effects |
| B. | dissipative effects |
| C. | depends on the given conditions |
| D. | none of the mentioned |
| Answer» A. no dissipative effects | |
| 258. | Irreversibility can be distinguished in how many types? |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» C. 2 | |
| 259. | Internal irreversibility is caused by |
| A. | internal dissipative effects |
| B. | friction, turbulence |
| C. | electrical resistance, magnetic hysteresis |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 260. | The external irreversibility occurs at the system boundary. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 261. | Which of the following is true? |
| A. | mechanical irreversibility is due to finite pressure gradient |
| B. | thermal irreversibility is due to finite temperature gradient |
| C. | chemical irreversibility is due to finite concentration gradient |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 262. | The magnitude of mechanical work is the |
| A. | product of the force and distance travelled perpendicular to the force |
| B. | product of the force and distance travelled parallel to the force |
| C. | sum of the force and distance travelled perpendicular to the force |
| D. | sum of the force and distance travelled parallel to the force |
| Answer» B. product of the force and distance travelled parallel to the force | |
| 263. | Work done by a system is taken to be |
| A. | positive |
| B. | negative |
| C. | zero |
| D. | varies according to situation |
| Answer» A. positive | |
| 264. | Work done on a system is taken to be |
| A. | positive |
| B. | negative |
| C. | zero |
| D. | varies according to situation |
| Answer» B. negative | |
| 265. | Work is a |
| A. | point function |
| B. | path function |
| C. | depends on the state |
| D. | none of the mentioned |
| Answer» B. path function | |
| 266. | Thermodynamic properties are |
| A. | point function |
| B. | path function |
| C. | depends on the state |
| D. | none of the mentioned |
| Answer» A. point function | |
| 267. | In the equation dV=(1/p)dW, (1/p) is known as |
| A. | volume factor |
| B. | pressure factor |
| C. | differential factor |
| D. | integration factor |
| Answer» D. integration factor | |
| 268. | Cyclic integral of a property is always |
| A. | zero |
| B. | one |
| C. | infinite value |
| D. | none of the mentioned |
| Answer» A. zero | |
| 269. | Constant pressure process is also known as |
| A. | isopiestic process |
| B. | isobaric process |
| C. | all of the mentioned |
| D. | none of the mentioned |
| Answer» C. all of the mentioned | |
| 270. | Work done in a quasi-static process |
| A. | depends on the path followed |
| B. | independent of the path followed |
| C. | depends only on the initial and final states |
| D. | none of the mentioned |
| Answer» A. depends on the path followed | |
| 271. | A saturation state is a state from which a change of phase may occur |
| A. | without a change of pressure or temperature |
| B. | with a change of pressure or temperature |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» A. without a change of pressure or temperature | |
| 272. | In which of the following state does water exist? |
| A. | saturated solid state |
| B. | saturated liquid state |
| C. | saturated vapour state |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 273. | 5 P-V DIAGRAM. |
| A. | saturated solid line |
| B. | saturated liquid lines |
| C. | saturated vapour line |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 274. | The triple point is a line on the p-V diagram, where all the three phases, solid, liquid and gas exist. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 276. | Which of the following statement is true? |
| A. | to the left of saturated solid line is the solid region |
| B. | between saturated solid line and saturated liquid line with respect to solidification there exists the solid-liquid mixture region |
| C. | between two saturated liquid lines is the compressed liquid region |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 277. | The greater the temperature, the is the vapour pressure. |
| A. | lower |
| B. | higher |
| C. | depends on the substance |
| D. | none of the mentioned |
| Answer» B. higher | |
| 278. | Phase change occurs at |
| A. | constant pressure |
| B. | constant temperature |
| C. | constant pressure and temperature |
| D. | none of the mentioned |
| Answer» C. constant pressure and temperature | |
| 279. | Which of the following statement is true? |
| A. | saturation temperature is a function of pressure |
| B. | saturation pressure is a function of temperature |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 280. | At absolute zero, an isotherm and an adiabatic are identical. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 281. | When the heat transferred isothermally |
| A. | doesnot, can, without |
| B. | exists, cannot, without |
| C. | exists, can, with |
| D. | none of the mentioned |
| Answer» B. exists, cannot, without | |
| 282. | First law of thermodynamics deals with |
| A. | conservation of mass |
| B. | conservation of momentum |
| C. | conservation of energy |
| D. | conservation of pressure |
| Answer» C. conservation of energy | |
| 283. | During a fluid flow, the temperature is developed due to |
| A. | increase in density |
| B. | change in pressure |
| C. | translational kinetic energy |
| D. | fluid level |
| Answer» C. translational kinetic energy | |
| 284. | The equation for the average kinetic energy is |
| A. | 0.5 kt |
| B. | 1.5 kt |
| C. | 2.5 kt |
| D. | 3.5 kt |
| Answer» B. 1.5 kt | |
| 285. | Entropy occurs due to |
| A. | change in macroscopic variables |
| B. | volumetric changes only |
| C. | mass changes only |
| D. | temperature only |
| Answer» A. change in macroscopic variables | |
| 286. | What is the equation of entropy? |
| A. | ratio of reversible transfer of heat to absolute temperature |
| B. | ratio of absolute temperature to reversible heat transfer |
| C. | ratio of adiabatic heat to macroscopic variables |
| D. | ratio of macroscopic variables to adiabatic heat |
| Answer» A. ratio of reversible transfer of heat to absolute temperature | |
| 287. | SI unit of enthalpy is |
| A. | joule/kgk |
| B. | joule/k |
| C. | joule/kg |
| D. | k/kg |
| Answer» C. joule/kg | |
| 288. | Which among this is not an exothermic reaction? |
| A. | combustion reaction |
| B. | neutralization reaction |
| C. | thermite reaction |
| D. | evaporating liquid water |
| Answer» D. evaporating liquid water | |
| 289. | What reaction takes place during photosynthesis? |
| A. | exothermic reaction |
| B. | endothermic reaction |
| C. | redox reaction |
| D. | combustion reaction |
| Answer» B. endothermic reaction | |
| 290. | The first law of thermodynamics doesn’t tell us whether a thermodynamic process is feasible or not. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 291. | According to Joule’s experiments, |
| A. | heat can be completely converted into work |
| B. | work can be completely converted into heat |
| C. | both heat and work are completely interchangeable |
| D. | all of the mentioned |
| Answer» B. work can be completely converted into heat | |
| 292. | Which of the following is true? |
| A. | work is a high grade energy |
| B. | heat is a low grade energy |
| C. | complete conversion of low grade energy into high grade energy in a cycle is impossible |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 293. | Boiler, turbine, condenser and pump together constitute a heat engine. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 294. | In a heat engine cycle, which of the following process occurs? |
| A. | heat is transferred from furnace to boiler |
| B. | work is produced in turbine rotor |
| C. | steam is condensed in condenser |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 295. | A thermal energy reservoir is a large body of |
| A. | small heat capacity |
| B. | large heat capacity |
| C. | infinite heat capacity |
| D. | none of the mentioned |
| Answer» C. infinite heat capacity | |
| 296. | Processes inside a thermal energy reservoir are quasi-static. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 297. | Carnot cycle is a reversible cycle. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 298. | Which if the following statements are true for a mechanical energy reservoir(MER)? |
| A. | it is a large body enclosed by an adiabatic impermeable wall |
| B. | stores work as ke or pe |
| C. | all processes within an mer are quasi- static |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 299. | The correct sequence of the processes taking place in a carnot cycle is |
| A. | adiabatic -> adiabatic -> isothermal -> isothermal |
| B. | adiabatic -> isothermal -> adiabatic -> isothermal |
| C. | isothermal -> isothermal -> adiabatic -> adiabatic |
| D. | isothermal -> adiabatic -> isothermal -> adiabatic |
| Answer» D. isothermal -> adiabatic -> isothermal -> adiabatic | |
| 301. | Efficiency of a reversible heat engine is given by | |
| A. | 1-(t1/t2) | |
| B. | 1-(t2/t1) | |
| C. | (t1/t2)-1 | |
| D. | (t2/t1)-1 | |
| Answer» B. 1-(t2/t1) | ||
| 302. | For a reversible refrigerator, Coefficient of Performance is given by |
| A. | t2/(t1-t2) |
| B. | t1/(t1-t2) |
| C. | t2/(t2-t1) |
| D. | t1/(t2-t1) |
| Answer» A. t2/(t1-t2) | |
| 303. | Entropy principle is the quantitative statement of the second law of thermodynamics. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 304. | Which of the following can be considered as an application of entropy principle? |
| A. | transfer of heat through a finite temperature difference |
| B. | mixing of two fluids |
| C. | maximum temperature obtainable from two finite bodies |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 305. | The final temperatures of two bodies, initially at T1 and T2 can range from |
| A. | (t1-t2)/2 to sqrt(t1*t2) |
| B. | (t1+t2)/2 to sqrt(t1*t2) |
| C. | (t1+t2)/2 to (t1*t2) |
| D. | (t1-t2)/2 to (t1*t2) |
| Answer» B. (t1+t2)/2 to sqrt(t1*t2) | |
| 306. | Which of the following processes exhibit external mechanical irreversibility? |
| A. | isothermal dissipation of work |
| B. | adiabatic dissipation of work |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 307. | Which of the following is an example of low grade energy? |
| A. | heat or thermal energy |
| B. | heat from nuclear fission or fusion |
| C. | heat from combustion of fossil fuel |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 308. | Which of the following is an example of high grade energy? |
| A. | mechanical work |
| B. | electrical energy |
| C. | water power and wind power |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 309. | The unavailable energy is the product of the lowest temperature of heat rejection and the change of entropy of system during the process of supplying heat. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 310. | The lowest practicable temperature of heat rejected is the |
| A. | given temperature |
| B. | 0k |
| C. | temperature of surroundings |
| D. | 273k |
| Answer» C. temperature of surroundings | |
| 311. | Exergy is lost due to |
| A. | irreversible heat transfer |
| B. | through finite temperature difference |
| C. | during the process of heat addition |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 312. | Which of the following is a type of energy? |
| A. | high grade energy |
| B. | low grade energy |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 313. | The complete conversion of heat into shaft- work is impossible. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 314. | Energy is said to be degraded each time it flows through a finite temperature difference. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 315. | When considering a finite energy source, its working fluid expands, |
| A. | reversibly |
| B. | adiabatically |
| C. | reversibly and adiabatically |
| D. | none of the mentioned |
| Answer» C. reversibly and adiabatically | |
| 316. | The entropy of any closed system can increase in which if the following way? |
| A. | by heat interaction in which there is entropy transfer |
| B. | dissipative effects or internal irreversibilities |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 317. | The entropy increase due to internal irreversibility is also called entropy production or entropy generation. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 318. | Which of the following statement is true? |
| A. | if the isentropic process is reversible, it must be adiabatic |
| B. | if the isentropic process is adiabatic, it cannot but be reversible |
| C. | if the process is adiabatic and reversible, it must be isentropic |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 319. | Lost work is given by |
| A. | pdv-dw |
| B. | pdv+dw |
| C. | -pdv-dw |
| D. | pdv*dw |
| Answer» A. pdv-dw | |
| 320. | Which of the following statement is false? |
| A. | for a reversible process, entropy generation is zero |
| B. | the entropy generation does not depend on the path the system follows |
| C. | for an irreversible process, entropy generation is greater than zero |
| D. | none of the mentioned |
| Answer» B. the entropy generation does not depend on the path the system follows | |
| 321. | Mass and energy are conserved quantities, but entropy is generally not conserved. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 322. | A chip dissipates 2 kJ of electric work and rejects it as heat transfer from its surface which is at 50°C to 25°C air. How much entropy is generated outside the chip? |
| A. | 0.419 j/k |
| B. | 0.519 j/k |
| C. | 0.619 j/k |
| D. | 0.719 j/k |
| Answer» B. 0.519 j/k | |
| 323. | Entropy increase dS of the system can be expressed as |
| A. | ds=ds(due to external heat interaction)- ds(due to internal irreversibility) |
| B. | ds=ds(due to external heat interaction)+ds(due to internal irreversibility) |
| C. | ds=-ds(due to external heat interaction)- ds(due to internal irreversibility) |
| D. | ds=-ds(due to external heat interaction)+ds(due to internal irreversibility) |
| Answer» B. ds=ds(due to external heat interaction)+ds(due to internal irreversibility) | |
| 324. | If the path A causes more entropy generation than path B, then |
| A. | path a is more irreversible than path b |
| B. | path a involves more lost work |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 326. | A chip dissipates 2 kJ of electric work and rejects it as heat transfer from its surface which is at 50°C to 25°C air. How much entropy is generated in the chip? |
| A. | 4.19 j/k |
| B. | 5.19 j/k |
| C. | 6.19 j/k |
| D. | 7.19 j/k |
| Answer» C. 6.19 j/k | |
| 327. | 15 = 6.19 J/K. |
| A. | 0.419 j/k |
| B. | 0.519 j/k |
| C. | 0.619 j/k |
| D. | 0.719 j/k |
| Answer» B. 0.519 j/k | |
| 328. | Second law efficiency can also be given as |
| A. | 1 / ( first law efficiency * carnot efficiency) |
| B. | carnot efficiency * first law efficiency |
| C. | carnot efficiency / first law efficiency |
| D. | first law efficiency / carnot efficiency |
| Answer» D. first law efficiency / carnot efficiency | |
| 329. | Second law efficiency is defined as |
| A. | actual exergy intake / minimum exergy intake |
| B. | minimum exergy intake / actual exergy intake |
| C. | actual exergy intake / maximum exergy intake |
| D. | maximum exergy intake / minimum exergy intake |
| Answer» B. minimum exergy intake / actual exergy intake | |
| 330. | For a power plant, second law efficiency can be given by desired output(W) / available energy(Wmax). |
| A. | true |
| B. | false |
| Answer» A. true | |
| 331. | In case of a heat pump, second law efficiency is given as |
| A. | (first law efficiency)*(1-ta/to) |
| B. | (first law efficiency)*(1+to/ta) |
| C. | (first law efficiency)*(1-to/ta) |
| D. | none of the mentioned |
| Answer» C. (first law efficiency)*(1-to/ta) | |
| 332. | Both first law efficiency and second law efficiency indicate how effectively the input has been converted into the product. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 333. | Which of the following curves meet at triple point? |
| A. | fusion curve and vaporization curve |
| B. | fusion curve and sublimation curve |
| C. | vaporization curve and sublimation curve |
| D. | fusion curve and vaporization curve and sublimation curve |
| Answer» D. fusion curve and vaporization curve and sublimation curve | |
| 334. | The slope of the fusion curve for water is |
| A. | negative |
| B. | positive |
| C. | zero |
| D. | none of the mentioned |
| Answer» A. negative | |
| 335. | The equation which forms the basis of the Mollier diagram is |
| A. | tds=-dh+vdp |
| B. | tds=dh+vdp |
| C. | tds=dh-vdp |
| D. | none of the mentioned |
| Answer» C. tds=dh-vdp | |
| 336. | Which of the following statements is true? |
| A. | the slope of an isobar on h-s coordinates is equal to the absolute saturation temperature at that pressure |
| B. | is the temperature remains constant, the slope will also remain constant |
| C. | if the temperature increases, the slope of the isobar will also increase |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 337. | Which of the following represents the latent heat of vaporization at a particular pressure. |
| A. | hf-hg |
| B. | hg-hf |
| C. | hf+hg |
| D. | none of the mentioned |
| Answer» B. hg-hf | |
| 338. | At critical pressure, value of Hg-Hf is |
| A. | two |
| B. | one |
| C. | zero |
| D. | infinity |
| Answer» C. zero | |
| 339. | In the Mollier diagram, the constant pressure lines diverge from one another. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 340. | Which of the following is a property of a pure substance? |
| A. | it has constant chemical composition throughout its mass |
| B. | it is a one-component system |
| C. | it may exist in one or more phases |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 341. | For water, as temperature increases, volume always increases? |
| A. | true |
| B. | false |
| Answer» B. false | |
| 342. | Which of the following exists in a p-V diagram for water? |
| A. | saturated solid line |
| B. | saturated liquid lines |
| C. | saturated vapour line |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 343. | The isotherm passing through the critical point is called the critical isotherm. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 344. | The properties of water are arranged in the steam tables as functions of |
| A. | pressure |
| B. | temperature |
| C. | pressure and temperature |
| D. | none of the mentioned |
| Answer» C. pressure and temperature | |
| 345. | The internal energy of saturated water at the triple point is |
| A. | 1 |
| B. | 0 |
| C. | -1 |
| D. | infinity |
| Answer» B. 0 | |
| 346. | The entropy of saturated water is chosen to be zero at triple point. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 347. | When a liquid and its vapour are in equilibrium at a certain pressure and temperature, then which of the following is required to identify the saturation state. |
| A. | pressure |
| B. | temperature |
| C. | both pressure and temperature |
| D. | pressure or temperature |
| Answer» D. pressure or temperature | |
| 348. | Saturated liquid or the saturated vapour has how many independent variables? |
| A. | one |
| B. | two |
| C. | three |
| D. | none of the mentioned |
| Answer» A. one | |
| 349. | If data are required for intermediate temperatures or pressures, linear interpolation is normally accurate. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 351. | When the temperature of a liquid is less than the saturation temperature at the given pressure, the liquid is called compressed liquid. | |
| A. | true | |
| B. | false | |
| Answer» A. true | ||
| 352. | Which of the following statement is true? |
| A. | a subcooled liquid is one which is cooled below its saturation temperature at a certain pressure |
| B. | subcooling is the difference between the saturation temperature and the actual liquid temperature |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 353. | Why is the steam not allowed to expand deep into the two phase region before it is taken to reheating? |
| A. | to control flow rate |
| B. | to control phase change |
| C. | to protect reheat tubes |
| D. | none of the mentioned |
| Answer» C. to protect reheat tubes | |
| 354. | Net Work output of the plant with reheat. |
| A. | decreases |
| B. | increases |
| C. | remains same |
| D. | none of the mentioned |
| Answer» B. increases | |
| 355. | What is the effect of decrease of reheat pressure on the quality of steam at turbine exhaust? |
| A. | decreases |
| B. | increases |
| C. | remains same |
| D. | none of the mentioned |
| Answer» B. increases | |
| 356. | The optimum reheat pressure for most of the power plants is how many times of the initial steam pressure? |
| A. | 0.1-0.15 |
| B. | 0.2-0.20 |
| C. | 0.2-0.25 |
| D. | 0.1-0.10 |
| Answer» C. 0.2-0.25 | |
| 357. | What is the most preferable dryness |
| A. | 0.99 |
| B. | 0.77 |
| C. | 0.66 |
| D. | 0.88 |
| Answer» D. 0.88 | |
| 358. | For pressure ratio = 1, efficiency = 0, then? |
| A. | reheat is used |
| B. | reheat is not used |
| C. | only reheat is used |
| D. | none of the mentioned |
| Answer» B. reheat is not used | |
| 359. | At critical point, value of Vg-Vf is |
| A. | two |
| B. | one |
| C. | zero |
| D. | infinity |
| Answer» C. zero | |
| 360. | Above the critical point, the isotherms are continuous curves. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 361. | A piston –cylinder device contains 0.06m3 of saturated water vapour at 350 kPa pressure. Determine the temperature and mass of the vapour inside the cylinder. |
| A. | 0.104 kg |
| B. | 0.124 kg |
| C. | 0.134 kg |
| D. | 0.114 kg |
| Answer» D. 0.114 kg | |
| 362. | A rigid tank contains 10 kg of water at 90°C. If 8 kg of the water is in the liquid form and the rest is in the vapour form, determine the pressure in the tank. |
| A. | 60.183 kpa |
| B. | 70.183 kpa |
| C. | 80.183 kpa |
| D. | 90.183 kpa |
| Answer» B. 70.183 kpa | |
| 363. | A rigid tank contains 10 kg of water at 90°C. If 8 kg of the water is in the liquid form and the rest is in the vapour form, determine the volume of the tank. |
| A. | 1.73 m3 |
| B. | 2.73 m3 |
| C. | 3.73 m3 |
| D. | 4.73 m3 |
| Answer» D. 4.73 m3 | |
| 364. | An 80 litre vessel contains 4 kg of R-134a at a pressure of 160 kPa. Determine the quality. |
| A. | 0.127 |
| B. | 0.137 |
| C. | 0.147 |
| D. | 0.157 |
| Answer» D. 0.157 | |
| 365. | Determine the specific volume of R-134a at 1 MPa and 50°C, using ideal gas equation of state. |
| A. | 0.022325 m3/kg |
| B. | 0.024325 m3/kg |
| C. | 0.025325 m3/kg |
| D. | 0.026325 m3/kg |
| Answer» B. 0.024325 m3/kg | |
| 366. | What is the unit of Heat rate? |
| A. | kj/kw |
| B. | kw/kj |
| C. | kj |
| D. | kw |
| Answer» A. kj/kw | |
| 367. | Rankine cycle operating on low pressure limit of p1 and high pressure limit of p2 |
| A. | has higher thermal efficiency than the carnot cycle operating between same pressure limits |
| B. | has lower thermal efficiency than carnot cycle operating between same pressure limits |
| C. | has same thermal efficiency as carnot cycle operating between same pressure limits |
| D. | may be more or less depending upon the magnitudes of p1 and p2 |
| Answer» A. has higher thermal efficiency than the carnot cycle operating between same pressure limits | |
| 368. | Rankine efficiency of a Steam Power Plant |
| A. | improves in summer as compared to that in winter |
| B. | improves in winter as compared to that in summer |
| C. | is unaffected by climatic conditions |
| D. | none of the mentioned |
| Answer» B. improves in winter as compared to that in summer | |
| 369. | Rankine cycle comprises of |
| A. | two isentropic processes and two constant volume processes |
| B. | two isentropic processes and two constant pressure processes |
| C. | two isothermal processes and two constant pressure processes |
| D. | none of the mentioned |
| Answer» B. two isentropic processes and two constant pressure processes | |
| 370. | In Rankine cycle, the work output from the turbine is given by |
| A. | change of internal energy between inlet and outlet |
| B. | change of enthalpy between inlet and outlet |
| C. | change of entropy between inlet and outlet |
| D. | change of temperature between inlet and outlet |
| Answer» B. change of enthalpy between inlet and outlet | |
| 371. | What is the actual turbine inlet temperature in Rankine cycle? |
| A. | 700c |
| B. | 800c |
| C. | 550c |
| D. | 1150c |
| Answer» C. 550c | |
| 372. | Rankine cycle efficiency of a good Steam Power Plant may be in the range of? |
| A. | 15 to 20% |
| B. | 35 to 45% |
| C. | 70 to 80% |
| D. | 90 to 95% |
| Answer» B. 35 to 45% | |
| 373. | A simple Rankine cycle produces 40 MW of power, 50 MW of process heat and rejects 60 MW of heat to the surroundings. What is the utilization factor of this co generation cycle neglecting the pump work? |
| A. | 50 |
| B. | 60 |
| C. | 70 |
| D. | 80 |
| Answer» B. 60 | |
| 374. | Why both reheating and regeneration is used together? |
| A. | the effect of reheat alone on efficiency is very small |
| B. | regeneration has a marked effect on efficiency |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 376. | Which of the following is true for an open heater? | |
| A. | it is simple, has low cost and low heat transfer capacity | |
| B. | a pump is required at each heater | |
| C. | both of the mentioned | |
| D. | none of the mentioned | |
| Answer» B. a pump is required at each heater | ||
| 377. | Deaerator is a type of open heater. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 378. | Which of the following is true for a closed heater? |
| A. | it requires a single pump regardless of the number of heaters |
| B. | it is costly |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 379. | The efficiency gain follows the law of diminishing return with the increase in the number of heaters. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 380. | Which of the following statement is true? |
| A. | in some cases, an increase in feedwater temperature may reduce the boiler efficiency |
| B. | number of heaters are optimized |
| C. | most often, five points of extraction are used |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 381. | The corrected gas equation is given by |
| A. | (p+a/(v2))(v+b)=rt |
| B. | (p-a/(v2))(v-b)=rt |
| C. | (p-a/(v2))(v+b)=rt |
| D. | (p+a/(v2))(v-b)=rt |
| Answer» D. (p+a/(v2))(v-b)=rt | |
| 382. | Which of the following statement is true about the correction terms? |
| A. | the coefficient a was introduced to account for the existence of mutual attraction between the molecules |
| B. | the term a/(v2) is called the force of cohesion |
| C. | the coefficient b was introduced to account for the volumes of the molecules and is known as co-volume |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 383. | Compressibility factor Z is given by |
| A. | rt/pv |
| B. | pv/rt |
| C. | (rt/pv)2 |
| D. | (pv/rt)2 |
| Answer» B. pv/rt | |
| 384. | For an ideal gas, Z has the value |
| A. | 0 |
| B. | 2 |
| C. | 1 |
| D. | infinity |
| Answer» C. 1 | |
| 385. | The magnitude of Z at a particular pressure and temperature indicates the extent of deviation of the gas from the ideal gas behaviour. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 386. | For the ideal gas equation, what assumptions are made? |
| A. | there is little or no attraction between the molecules of the gas |
| B. | the volume occupied by the molecules is negligibly small compared to the volume of the gas |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 387. | When does a real gas obey the ideal gas equation closely? |
| A. | at high pressure and low temperature |
| B. | at low pressure and high temperature |
| C. | at low pressure and temperature |
| D. | at high pressure and temperature |
| Answer» B. at low pressure and high temperature | |
| 388. | The real gases deviate from the ideal gas equation when the pressure increases. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 389. | Real gases conform more closely with the van der Waals equation of state than the ideal gas equation of state. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 390. | What is the pressure of H2 with compressibility 0.6, molar volume 5 liter/mole at 27oC? |
| A. | 2.9 atm |
| B. | 5.4 atm |
| C. | 9.6 atm |
| D. | 14.5 atm view answer |
| Answer» A. 2.9 atm | |
| 391. | 3 COMPRESSIBILITY CHART AND ITS USE |
| A. | 300.5 k |
| B. | 304.5 k |
| C. | 310 k |
| D. | 312.5 k |
| Answer» B. 304.5 k | |
| 392. | What is the pressure of 80 grams of CH4 with compressibility 5, with 10 liter volume at 27oC? |
| A. | 10.5 atm |
| B. | 28.9 atm |
| C. | 44.2 atm |
| D. | 61.5 atm view answer |
| Answer» D. 61.5 atm view answer | |
| 393. | What is the compressibility of neon (molar mass = 20) with density 20 g/liter at 27oC and 100 atm? |
| A. | 2.1 |
| B. | 3.5 |
| C. | 4 |
| D. | 6.8 |
| Answer» C. 4 | |
| 394. | 90 g glucose is filled in a container at 10 atm, if the volume of container is 2 liter, what is the temperature of glucose (z = 1.5)? |
| A. | 25.4oc |
| B. | 51.7oc |
| C. | 76.9oc |
| D. | 103.5oc |
| Answer» B. 51.7oc | |
| 395. | at 1 atm and 27oC? |
| A. | 23.4 liter |
| B. | 37.5 liter |
| C. | 42.1 liter |
| D. | 59.6 liter view answer |
| Answer» A. 23.4 liter | |
| 396. | 39 grams of benzene (z = 1.4) is filled in a container of volume 10 liter at 27oC, what is the pressure of container? |
| A. | 1.7 atm |
| B. | 1.9 atm |
| C. | 2.2 atm |
| D. | 2.5 atm view answer |
| Answer» A. 1.7 atm | |
| 397. | Which of the following relation is correct? |
| A. | du=tds-pdv |
| B. | dh=tds+vdp |
| C. | dg=vdp-sdt |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 398. | Maxwell’s equations consists of equations. |
| A. | four |
| B. | three |
| C. | two |
| D. | one |
| Answer» A. four | |
| 399. | The first TdS equation is |
| A. | tds=cv*dt + t(∂t/∂p)dv |
| B. | tds=cv*dt – t(∂p/∂t)dv |
| C. | tds=cv*dt + t(∂p/∂t)dv |
| D. | tds=cv*dt – t(∂t/∂p)dv |
| Answer» C. tds=cv*dt + t(∂p/∂t)dv | |
| 401. | For getting TdS equations, we assume entropy to be a function of T and V and also of T and p. | |
| A. | true | |
| B. | false | |
| Answer» A. true | ||
| 402. | During phase transitions like vaporization, melting and sublimation |
| A. | pressure and temperature remains constant |
| B. | volume and entropy changes |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 403. | Which of the following requirement is satisfied by a phase change of the first order? |
| A. | there are changes of volume and entropy |
| B. | the first-order derivative of the gibbs function changes discontinuously |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 404. | The vapour pressure p in kPa at |
| A. | p = 101.325 exp (88/r)(1+t/tb) |
| B. | p = 101.325 exp (88/r)(1+tb/t) |
| C. | p = 101.325 exp (88/r)(1-t/tb) |
| D. | p = 101.325 exp (88/r)(1-tb/t) |
| Answer» D. p = 101.325 exp (88/r)(1-tb/t) | |
| 405. | The vapour pressure curve is of the form ln(p) = A + B/T + C*lnT + DT. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 406. | According to Trouton’s rule, the ratio of latent heat of vaporization to the boiling point at 1.013 bar is |
| A. | 77 kj/kgmol k |
| B. | 88 kj/kgmol k |
| C. | 99 kj/kgmol k |
| D. | 100 kj/kgmol k |
| Answer» B. 88 kj/kgmol k | |
| 407. | Estimate the freezing temperature of liquid water at a pressure of 30 MPa. |
| A. | -2.2°c |
| B. | 0°c |
| C. | -0.2°c |
| D. | -1.2°c |
| Answer» A. -2.2°c | |
| 408. | The expression nRT/V is called the partial pressure of a gas. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 409. | The gas constant of the mixture is the of the gas constants of the components. |
| A. | average |
| B. | weighted mean |
| C. | sum |
| D. | difference of the highest and the lowest |
| Answer» B. weighted mean | |
| 410. | A quantity called partial volume of a component of mixture is used. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 411. | When gases which are at equal pressure and temperature are mixed adiabatically without work, then |
| A. | internal energy of the gaseous system remains constant |
| B. | heat transfer of the gaseous system remains constant |
| C. | entropy of the gaseous system remains constant |
| D. | all of the mentioned |
| Answer» A. internal energy of the gaseous system remains constant | |
| 412. | The fact that internal energy of a mixture is equal to the sum of the partial internal energies of the gases can also be applied to properties like H,Cv,Cp,S,F, and G. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 413. | Which of the following statement is true? |
| A. | the chart is plotted for pressure equal to 760mm hg |
| B. | the constant wbt line represents adiabatic saturation process |
| C. | the constant wbt line coincides with constant enthalpy line |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 414. | In sensible heating or cooling, |
| A. | work done remains constant |
| B. | dry bulb temperature or air remains constant |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» A. work done remains constant | |
| 415. | Cooling and dehumidification of air is done in summer air conditioning. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 416. | Heating and humidification is done in |
| A. | summer air conditioning |
| B. | winter air conditioning |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» B. winter air conditioning | |
| 417. | Which of the following is an absorbent? |
| A. | silica gel |
| B. | activated alumina |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 418. | When air passes through silica gel, |
| A. | it absorbs water vapour molecules |
| B. | latent heat of condensation is released |
| C. | dbt of air increases |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 419. | In adiabatic evaporative cooling, heat transfer between chamber and surroundings is |
| A. | zero |
| B. | high |
| C. | low |
| D. | none of the mentioned |
| Answer» A. zero | |
| 420. | The cooling tower uses the phenomenon of evaporative cooling to cool warm water above the dbt of air. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 421. | Cooling towers are rated in terms of |
| A. | approach |
| B. | range |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 422. | Dry air consists of |
| A. | oxygen, nitrogen |
| B. | carbon dioxide |
| C. | hydrogen, argon |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 423. | Complete dry air exists in nature. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 424. | Which of the following is true?(here pa=partial pressure of dry air, pw=partial pressure of water vapour, p=atmospheric pressure) |
| A. | p=pw |
| B. | p=pa |
| C. | p=pw + pa |
| D. | all of the mentioned |
| Answer» C. p=pw + pa | |
| 426. | When pw is very small, |
| A. | saturation temperature of water vapour at pw is less than atmospheric temperature |
| B. | water vapour in air exists in superheated state |
| C. | air is said to be in unsaturated state |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 427. | Relative humidity is defined as |
| A. | (saturation pressure of pure water) / pw |
| B. | pw / (saturation pressure of pure water) |
| C. | (saturation pressure of pure water) / p |
| D. | p / (saturation pressure of pure water) |
| Answer» B. pw / (saturation pressure of pure water) | |
| 428. | For saturated air, relative humidity is 0%. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 429. | If water is injected into a container with has unsaturated air, |
| A. | water will evaporate |
| B. | moisture content of air will decrease |
| C. | pw will decrease |
| D. | all of the mentioned |
| Answer» A. water will evaporate | |
| 430. | Humidity ratio is given by the ratio of |
| A. | (mass of dry air per unit mass of water vapour)^2 |
| B. | 1/(mass of dry air * mass of water vapour) |
| C. | water vapour mass per unit mass of dry air |
| D. | mass of dry air per unit mass of water vapour |
| Answer» C. water vapour mass per unit mass of dry air | |
| 431. | Which of the following statement is true? |
| A. | dew point temperature is the temperature at which water vapour starts condensing |
| B. | dry bulb temperature is recorded by thermometer with dry bulb |
| C. | wet bulb temperature is recorded by thermometer when bulb is covered with a cotton wick which is saturated with water |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 432. | The wet bulb temperature is the temperature recorded by moistened bulb. |
| A. | lowest |
| B. | highest |
| C. | atmospheric |
| D. | none of the mentioned |
| Answer» A. lowest | |
| 433. | Air can be cooled and dehumidified by |
| A. | circulating chilled water in tube across air flow |
| B. | placing evaporator coil across air flow |
| C. | spraying chilled water to air |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 434. | When two equilibrium states are infinitesimally near, |
| A. | dq/t=ds |
| B. | dq/t>ds |
| C. | dq/t<ds |
| D. | none of the mentioned |
| Answer» A. dq/t=ds | |
| 435. | The greater the temperature, the is the vapour pressure. |
| A. | lower |
| B. | higher |
| C. | depends on the substance |
| D. | none of the mentioned |
| Answer» B. higher | |
| 436. | It is necessary to have a temperature difference to obtain work of any cycle. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 437. | The absolute thermodynamic temperature scale is also known as |
| A. | celsius scale |
| B. | kelvin scale |
| C. | fahrenheit scale |
| D. | none of the mentioned |
| Answer» B. kelvin scale | |
| 438. | In defining the temperature scale, the standard reference point is taken as |
| A. | zero kelvin |
| B. | boiling point of water |
| C. | triple point of water |
| D. | none of the mentioned |
| Answer» C. triple point of water | |
| 439. | When the heat transferred isothermally between the given decreases, the temperature |
| A. | isotherms, increases |
| B. | isotherms, decreases |
| C. | adiabatics, increases |
| D. | adiabatics, decreases |
| Answer» D. adiabatics, decreases | |
| 440. | If a system undergoes a reversible isothermal process without transfer of heat, the temperature at which this process takes place is called |
| A. | absolute zero |
| B. | triple point of water |
| C. | boiling point of water |
| D. | none of the mentioned |
| Answer» A. absolute zero | |
| 441. | A definite zero point on the absolute temperature scale but this point be reached violation of the second law. |
| A. | doesnot, can, without |
| B. | exists, cannot, without |
| C. | exists, can, with |
| D. | none of the mentioned |
| Answer» B. exists, cannot, without | |
| 442. | Which law is stated here, “It is impossible to reduce any system to the absolute zero of temperature in a finite number of operations. |
| A. | first law of thermodynamics |
| B. | second law of thermodynamics |
| C. | third law of thermodynamics |
| D. | none of the mentioned |
| Answer» C. third law of thermodynamics | |
| 443. | The statement of third law is also called the Fowler-Guggenheim statement of the third law. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 444. | The Kelvin temperature is numerically equal to the and may be measured by means of a |
| A. | gas temperature, liquid thermometer |
| B. | ideal gas temperature, gas thermometer |
| C. | ideal gas temperature, liquid thermometer |
| D. | none of the mentioned |
| Answer» B. ideal gas temperature, gas thermometer | |
| 445. | During a fluid flow, the temperature is developed due to |
| A. | increase in density |
| B. | change in pressure |
| C. | translational kinetic energy |
| D. | fluid level |
| Answer» C. translational kinetic energy | |
| 446. | The equation for the average kinetic energy is |
| A. | 0.5 kt |
| B. | 1.5 kt |
| C. | 2.5 kt |
| D. | 3.5 kt |
| Answer» B. 1.5 kt | |
| 447. | Entropy occurs due to |
| A. | change in macroscopic variables |
| B. | volumetric changes only |
| C. | mass changes only |
| D. | temperature only |
| Answer» A. change in macroscopic variables | |
| 448. | Efficiency of a heat engine is defined as |
| A. | total heat output / net work input |
| B. | total heat input / net work output |
| C. | net work output / total heat input |
| D. | net work input / total heat output |
| Answer» C. net work output / total heat input | |
| 449. | A TER which transfers heat to system is called and one which receives heat is called |
| A. | source, sink |
| B. | sink, source |
| C. | sink, sink |
| D. | source, source |
| Answer» A. source, sink | |
| 451. | 2 STATEMENTS OF SECOND LAW AND ITS COROLLARIES. CARNOT CYCLE REVERSED CARNOT CYCLE, PERFORMANCE. CLAUSIUS INEQUALITY. |
| A. | high, low, receives |
| B. | low, high, receives |
| C. | high, low, gives |
| D. | low, high, gives |
| Answer» B. low, high, receives | |
| 452. | According to Carnot’s theorem, all heat engines operating between a given constant temperature source and sink, none has a higher efficiency than a reversible engine. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 453. | The efficiency of all reversible heat engines operating between the same heat reservoirs is |
| A. | same |
| B. | independent of the nature of working substance |
| C. | independent of the amount of working substance |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 454. | For a reversible heat pump, COP is given by |
| A. | t2/(t1-t2) |
| B. | t1/(t1-t2) |
| C. | t2/(t2-t1) |
| D. | t1/(t2-t1) |
| Answer» B. t1/(t1-t2) | |
| 455. | The entropy of an isolated system can never |
| A. | increase |
| B. | decrease |
| C. | be zero |
| D. | none of the mentioned |
| Answer» B. decrease | |
| 456. | According to entropy principle, the entropy of an isolated system can never decrease and remains constant only when the process is reversible. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 457. | Entropy may decrease locally at some region within the isolated system. How can this statement be justified? |
| A. | this cannot be possible |
| B. | this is possible because entropy of an isolated system can decrease. |
| C. | it must be compensated by a greater increase of entropy somewhere within the system. |
| D. | none of the mentioned |
| Answer» C. it must be compensated by a greater increase of entropy somewhere within the system. | |
| 458. | The final temperatures of two bodies, initially at T1 and T2 can range from |
| A. | (t1-t2)/2 to sqrt(t1*t2) |
| B. | (t1+t2)/2 to sqrt(t1*t2) |
| C. | (t1+t2)/2 to (t1*t2) |
| D. | (t1-t2)/2 to (t1*t2) |
| Answer» B. (t1+t2)/2 to sqrt(t1*t2) | |
| 459. | The part of available for conversion is referred to |
| A. | high grade energy, available energy |
| B. | low grade energy, available energy |
| C. | low grade energy, unavailable energy |
| D. | high grade energy, unavailable energy |
| Answer» B. low grade energy, available energy | |
| 460. | The obtainable from a certain heat input in a cyclic heat engine is called |
| A. | minimum work output, available energy |
| B. | maximum work output, available energy |
| C. | minimum work input, unavailable energy |
| D. | none of the mentioned |
| Answer» B. maximum work output, available energy | |
| 461. | 4 APPLICATIONS OF II LAW. HIGH AND LOW GRADE ENERGY. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 462. | The available energy is known as and the unavailable energy is known as |
| A. | energy, exergy |
| B. | exergy, energy |
| C. | both are called exergy |
| D. | both are called energy |
| Answer» B. exergy, energy | |
| 463. | Whenever heat is transferred through a finite temperature difference, there is always a decrease in the availability of energy so transferred. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 464. | Any thermodynamic process is accompanied by entropy generation. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 465. | The rate of entropy increase of the control volume or the net rate of entropy transfer to it. |
| A. | exceeds or is less than |
| B. | exceeds, is equal to |
| C. | is less than, or equal to |
| D. | none of the mentioned |
| Answer» B. exceeds, is equal to | |
| 466. | The rate at which entropy is transferred out must the rate at which entropy enters the control volume. |
| A. | be less than |
| B. | equal to |
| C. | exceed |
| D. | none of the mentioned |
| Answer» C. exceed | |
| 467. | The first law efficiency is defined as the ratio of the output energy to the input energy. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 468. | With the concept of exergy available, which of the following is possible? |
| A. | to analyse means of minimizing the consumption of available energy to perform a given process |
| B. | to ensure most efficient possible conversion of energy |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 469. | If work is involved, Amin= and if heat is involved, Amin= |
| A. | w, q(1+to/t) |
| B. | w, q(1-to/t) |
| C. | q(1+to/t), w |
| D. | q(1-to/t), w |
| Answer» B. w, q(1-to/t) | |
| 470. | If solar energy Qr is available at a reservoir storage temperature of Tr and if quantity of heat Qa is transferred by the solar collector at temperature Ta, then which of the following is true? |
| A. | first law efficiency = qa/qr |
| B. | second law efficiency = exergy output / exergy input |
| C. | second law efficiency = (first law efficiency)*(1-to/ta)/(1-to/tr) |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 471. | For proper utilization of exergy, it is desirable to make first law efficiency and the source and use temperatures should |
| A. | as close to unity, be different |
| B. | as close to unity, match |
| C. | as close to zero, match |
| D. | as close to zero, be different |
| Answer» B. as close to unity, match | |
| 472. | The slopes of sublimation and vaporization curves for all substances are |
| A. | negative |
| B. | positive |
| C. | zero |
| D. | none of the mentioned |
| Answer» B. positive | |
| 473. | When does a vapour become superheated? |
| A. | when the temperature of vapour is less than the saturation temperature at given pressure |
| B. | when the temperature of vapour is more than the saturation temperature at given pressure |
| C. | when the temperature of vapour is equal to the saturation temperature at given pressure |
| D. | none of the mentioned |
| Answer» B. when the temperature of vapour is more than the saturation temperature at given pressure | |
| 474. | The properties of liquid with pressure. |
| A. | do not vary |
| B. | vary largely |
| C. | vary little |
| D. | none of the mentioned |
| Answer» C. vary little | |
| 476. | Which of the following problems are posed by increasing the number of reheats? |
| A. | cost & fabrication problems arise |
| B. | heat transfer problems arise |
| C. | frictional losses arise |
| D. | none of the mentioned |
| Answer» A. cost & fabrication problems arise | |
| 477. | What is the most preferable dryness fraction of the exhaust steam? |
| A. | 0.99 |
| B. | 0.77 |
| C. | 0.66 |
| D. | 0.88 |
| Answer» D. 0.88 | |
| 478. | Which of the following represents the specific volume during phase transition. |
| A. | vf-vg |
| B. | vg-vf |
| C. | vf+vg |
| D. | none of the mentioned |
| Answer» B. vg-vf | |
| 479. | An 80 litre vessel contains 4 kg of R-134a at a pressure of 160 kPa. Determine the volume occupied by the vapour phase. |
| A. | 0.0775 m3 |
| B. | 0.0575 m3 |
| C. | 0.0975 m3 |
| D. | 0.0375 m3 |
| Answer» A. 0.0775 m3 | |
| 480. | Rankine cycle comprises of |
| A. | two isentropic processes and two constant volume processes |
| B. | two isentropic processes and two constant pressure processes |
| C. | two isothermal processes and two constant pressure processes |
| D. | none of the mentioned |
| Answer» B. two isentropic processes and two constant pressure processes | |
| 481. | In Rankine cycle, the work output from the turbine is given by |
| A. | change of internal energy between inlet and outlet |
| B. | change of enthalpy between inlet and outlet |
| C. | change of entropy between inlet and outlet |
| D. | change of temperature between inlet and outlet |
| Answer» B. change of enthalpy between inlet and outlet | |
| 482. | Which of the following contributes to the improvement of efficiency of Rankine cycle in a Thermal Power Plant? |
| A. | reheating of steam at intermediate stage |
| B. | regeneration use of steam for heating boiler feed water |
| C. | use of high pressures |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 483. | A simple Rankine cycle operates the Boiler at 3 MPa with an outlet temperature of 350°C and the Condenser at 50 kPa. Assuming ideal operation and processes, what is the thermal efficiency of this cycle? |
| A. | 7.7 |
| B. | 17.7 |
| C. | 27.7 |
| D. | 37.7 |
| Answer» C. 27.7 | |
| 484. | How many types of feedwater heaters are present? |
| A. | one |
| B. | two |
| C. | three |
| D. | four |
| Answer» B. two | |
| 485. | The temperature of feedwater leaving a heater is the saturation temperature at steam extraction pressure. |
| A. | less than |
| B. | equal to |
| C. | more than |
| D. | none of the mentioned |
| Answer» A. less than | |
| 486. | The following also gave two-constant equations of state. |
| A. | berthelot |
| B. | dieterici |
| C. | redlich-kwong |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 487. | Which of the following is true about compressibility of real gases? |
| A. | z = 1 |
| B. | z < 1 |
| C. | z > 1 |
| D. | both z < 1 and z > 1 view answer |
| Answer» D. both z < 1 and z > 1 view answer | |
| 488. | 1 mole of cyclohexane (z = 1.2) is filled in a container at 27oC and 4 atm, what is the volume of container? |
| A. | 3.8 liter |
| B. | 4.4 liter |
| C. | 5.6 liter |
| D. | 7.4 liter view answer |
| Answer» D. 7.4 liter view answer | |
| 489. | If a relation exists among variables x,y,z then z may be expressed as a function of x and y as, dz=Mdx+Ndy . |
| A. | true |
| B. | false |
| Answer» A. true | |
| 490. | A pure substance which exists in a single phase has independent variables. |
| A. | zero |
| B. | one |
| C. | two |
| D. | three |
| Answer» C. two | |
| 491. | Which of the following is not a Maxwell equation? |
| A. | (∂t/∂v) = -(∂p/∂s) |
| B. | (∂t/∂p) = -(∂v/∂s) |
| C. | (∂p/∂t) = (∂s/∂v) |
| D. | (∂v/∂t) = -(∂s/∂p) |
| Answer» B. (∂t/∂p) = -(∂v/∂s) | |
| 492. | The Clausius-Clapeyron equation is given by |
| A. | dp/dt = l / t(vf+vi) |
| B. | dp/dt = l / t(vf-vi) |
| C. | dt/dp = l / t(vf+vi) |
| D. | dt/dp = l / t(vf-vi) |
| Answer» B. dp/dt = l / t(vf-vi) | |
| 493. | Water on melting and has the fusion curve with a slope. |
| A. | contracts, negative |
| B. | contracts, positive |
| C. | expands, negative |
| D. | expands, positive |
| Answer» A. contracts, negative | |
| 494. | At the triple point, l(sublimation) = l(vaporization) – l(fusion). |
| A. | true |
| B. | false |
| Answer» B. false | |
| 495. | The slope of sublimation curve is the slope of the vaporization curve at triple point. |
| A. | equal to |
| B. | less than |
| C. | greater than |
| D. | none of the mentioned |
| Answer» C. greater than | |
| 496. | An application requires R-12 at −140°C. The triple-point temperature is −157°C. Find the pressure of the saturated vapour at the required condition. |
| A. | 0.0058 kpa |
| B. | 0.0098 kpa |
| C. | 0.0068 kpa |
| D. | 0.0088 kpa |
| Answer» B. 0.0098 kpa | |
| 497. | The expression which represents the pressure exerted by a gas is |
| A. | nvrt |
| B. | nrt/v |
| C. | v/nrt |
| D. | 1/nvrt |
| Answer» B. nrt/v | |
| 498. | Which of the following relation is correct? |
| A. | mole fraction of the kth gas = moles of the kth gas / total number of moles of gas |
| B. | partial pressure of kth gas = (mole fraction of the kth gas)*(sum of the partial pressures) |
| C. | sum of mole fractions of all the gases is unity |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 499. | The total entropy of a mixture of gases is the of the partial entropies. |
| A. | average |
| B. | weighted mean |
| C. | sum |
| D. | difference of the highest and the lowest |
| Answer» C. sum | |
| 501. | The degree of saturation is the ratio of |
| A. | (saturated specific humidity / actual specific humidity)^2 |
| B. | 1/(saturated specific humidity * actual specific humidity) |
| C. | saturated specific humidity / actual specific humidity |
| D. | actual specific humidity / saturated specific humidity |
| Answer» D. actual specific humidity / saturated specific humidity | |
| 502. | At any dbt, the the difference of wbt reading below below dbt, is the amount of water vapour held in mixture. |
| A. | smaller, smaller |
| B. | greater, greater |
| C. | greater, smaller |
| D. | smaller, greater |
| Answer» C. greater, smaller | |
| 503. | When unsaturated air flows over a sheet of water in an insulated chamber |
| A. | specific humidity of air decreases |
| B. | the water evaporates |
| C. | both air and water are cooled during evaporation |
| D. | all of the mentioned |
| Answer» A. specific humidity of air decreases | |
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