Thermodynamics Mechanical Engineering Objective Questions PDF

Prepared by BILAL NASIR 152 TOP Thermodynamics - Mechanical Engineering Multiple choice Questions and Answers List Thermodynamics Questions and Answers pdf free download 1. Which of the following variables controls the physical properties of a perfect gas (a) pressure (b) temperature (c) volume (d)...

Prepared by BILAL NASIR 152 TOP Thermodynamics - Mechanical Engineering Multiple choice Questions and Answers List Thermodynamics Questions and Answers pdf free download 1. Which of the following variables controls the physical properties of a perfect gas (a) pressure (b) temperature (c) volume (d) all of the above (e) atomic mass. Ans: d 2. Which of the following laws is applicable for the behavior of a perfect gas (a) Boyle's law (b) Charles'law (c) Gay-Lussac law (d) all of the above (e) Joule's law. Ans: d 3. The unit of temperature in S.I. units is (a) Centigrade (b) Celsius (c) Fahrenheit (d) Kelvin (e) Rankine. Ans: d 4. The unit of mass in S.I. units is (a) kilogram (b) gram (c) tonne (d) quintal (e) newton. Ans: a 5. The unit of time in S.I. units is (a) second (b) minute (c) hour (d) day (e) year. Ans: a Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 6. The unit of length in S.I. units is (a) meter (b) centimeter (c) kilometer (d) millimeter. Ans: a 7. The unit of energy in S.I. units is (a) watt (b) joule (c) joule/s (d) joule/m (e) joule m. Ans: b 8. According to Gay-Lussac law for a perfect gas, the absolute pressure of given mass varies directly as (a) temperature (b) absolute (c) absolute temperature, if volume is kept constant (d) volume, if temperature is kept constant (e) remains constant,if volume and temperature are kept constant. Ans: c 9. An ideal gas as compared to a real gas at very high pressure occupies (a) more volume (b) less volume (c) same volume (d) unpredictable behaviour (e) no such correlation. Ans: a 10. General gas equation is (a) PV=nRT (b) PV=mRT (d) PV = C (c) PV=KiRT (e) Cp-Cv = Wj Ans: b 11. According to Dalton's law, the total pres sure of the mixture of gases is equal to (a) greater of the partial pressures of all (b) average of the partial pressures of all (c) sum of the partial pressures of all (d) sum of the partial pressures of all divided by average molecular weight (e) atmospheric pressure. Ans: c 12. Which of the following can be regarded as gas so that gas laws could be applicable, Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR within the commonly encountered temperature limits. (a) 02, N2, steam, C02 (b) Oz, N2, water vapour (c) S02, NH3, C02, moisture (d) 02, N2, H2, air (e) steam vapours, H2, C02. Ans: d 13. The unit of pressure in S.I. units is (a) kg/cm2 (b) mm of water column (c) pascal (d) dynes per square cm (e) bars Ans: c 14. A closed system is one in which (a) mass does not cross boundaries of the system, though energy may do so (b) mass crosses the boundary but not the energy (c) neither mass nor energy crosses the boundaries of the system (d) both energy and mass cross the boundaries of the system (e) thermodynamic reactions take place. Ans: a 15. Temperature of a gas is produced due to (a) its heating value (b) kinetic energy of molecules (c) repulsion of molecules (d) attraction of molecules (e) surface tension of molecules. Ans: b 16. According to kinetic theory of gases, the absolute zero temperature is attained when (a) volume of the gas is zero (b) pressure of the gas is zero (c) kinetic energy of the molecules is zero (d) specific heat of gas is zero (e) mass is zero. Ans: c 17. Kinetic theory of gases assumes that the collisions between the molecules are (a) perfectly elastic (b) perfectly inelastic (c) partly elastic (d) partly inelastic (e) partly elastic and partly inelastic. Ans: a 18. The pressure'of a gas in terms of its mean kinetic energy per unit volume E is Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR equal to (a) E/3 (b) E/2 (c) 3E/4 (d)2E/3 (e) 5E/4. Ans: d 19. Kinetic energy of the molecules in terms of absolute temperature (T) is proportional to (a) T (b) j (c) J2 (d) Vr (e) 1/Vr. Ans: a 20. Superheated vapour behaves (a) exactly as gas (b) as steam (c) as ordinary vapour (d) approximately as a gas (e) as average of gas and vapour. Ans: d 21. Absolute zero pressure will occur (a) at sea level (b) at the center of the earth (c) when molecular momentum of the system becomes zero (d) under vacuum conditions (e) at a temperature of - 273 °K Ans: c 22. No liquid can exist as liquid at (a) - 273 °K (b) vacuum (c) zero pressure (d) centre of earth (e) in space. Ans: c 23. The unit of power in S.I. units is (a) newton (b) pascal (c) erg (d) watt (e) joule. Ans: d 24. The condition of perfect vacuum, i.e., absolute zero pressure can be attained at Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (a) a temperature of - 273.16°C (b) a temperature of 0°C (c) a temperature of 273 °K (d) a negative pressure and 0°C temperature (e) can't be attained. Ans: a 25. Intensive property of a system is one whose value (a) depends on the mass of the system, like volume (b) does not depend on the mass of the system, like temperature, pressure, etc. (c) is not dependent on the path followed but on the state (d) is dependent on the path followed and not on the state (e) remains constant. Ans: b 26. Specific heat of air at constant pressure is equal to (a) 0.17 (b) 0.21 (c) 0.24 (d) 1.0 (e) 1.41 Ans: c 27. Characteristic gas constant of a gas is equal to (a) C/Cv (b) Cv/Cp (c) Cp - Cv (d) Cp + Cv (e) Cp x Cv Ans: c 28. The behaviour of gases can be fully determined by (a) 1 law (b) 2 laws (c) 3 laws (d) 4 laws Ans: d 29. The ratio of two specific heats of air is equal to (a) 0.17 (b) 0.24 (c) 0.1 (d) 1.41 (e) 2.71. Ans: d 30. Boyle's law i.e. pV = constant is applicable to gases under (a) all ranges of pressures (b) only small range of pressures (c) high range of pressures Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (d) steady change of pressures (e) atmospheric conditions. Ans: b 31. Which law states that the internal energy of a gas is a function of temperature (a) Charles' law (b) Joule's law (c) Regnault's law (d) Boyle's law (e) there is no such law. Ans: b 32. The same volume of all gases would represent their (a) densities (b) specific weights (c) molecular weights (d) gas characteristic constants (e) specific gravities. Ans: c 33. Which law states that the specific heat of a gas remains constant at all temperatures and pressures (a) Charles' Law (b) Joule's Law (c) Regnault's Law (d) Boyle's Law (e) there is no such law. Ans: c 34. An open system is one in which (a) mass does not cross boundaries of the system, though energy may do so (b) neither mass nor energy crosses the boundaries of the system (c) both energy and mass cross the boundaries of the system (d) mass crosses the boundary but not the energy (e) thermodynamic reactions do not occur. Ans: c 35. According to which law, all perfect gases change in volume by l/273th of their original volume at 0°C for every 1°C change in temperature when pressure remains constant (a) Joule's law (b) Boyle's law (c) Regnault's law (d) Gay-Lussac law (e) Charles' law. Ans: e 36. Gases have (a) only one value of specific heat (b) two values of specific heat Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) three values of specific heat (d) no value of specific heat (e) under some conditions one value and sometimes two values of specific heat. Ans: b 37. According to Avogadro's Hypothesis (a) the molecular weights of all the perfect gases occupy the same volume under same conditions of pressure and temperature (b) the sum of partial pressure of mixture of two gases is sum of the two (c) product of the gas constant and the molecular weight of an ideal gas is constant (d) gases have two values of specific heat (e) all systems can be regarded as closed systems. Ans: a 38. Extensive property of a system is one whose value (a) depends on the mass of the system like volume (b) does not depend on the mass of the system, like temperature, pressure, etc. (c) is not dependent on the path followed but on the state (d) is dependent on the path followed and not on the state (e) is always constant. Ans: a 39. Work done in a free expansion process is (a) + ve (b) -ve (c) zero (d) maximum (e) minimum. Ans: c 40. The statement that molecular weights of all gases occupy the same volume is known as (a) Avogadro's hypothesis (b) Dalton's law (c) Gas law (d) Law of thermodynamics (e) Joule's law. Ans: a 41. To convert volumetric analysis to gravimetric analysis, the relative volume of each constituent of the flue gases is (a) divided by its molecular weight (b) multiplied by its molecular weight (c) multiplied by its density (d) multiplied by its specific weight (e) divided by its specific weight. Ans: b 42. If a gas is heated against a pressure, keeping the volume constant, then work done will be equal to Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (a) + v (b) - ve (c) zero (d) pressure x volume (e) any where between zero and infinity. Ans: c 43. An isolated system is one in which (a) mass does not cross boundaries of the system, though energy may do so (b) neither mass nor energy crosses the boundaries of the system (c) both energy and mass cross the boundaries of the system (d) mass crosses the boundary but not the energy (e) thermodynamic reactions do not occur. Ans: b 44. Properties of substances like pressure, temperature and density, in thermodynamic coordinates are (a) path functions (b) point functions (c) cyclic functions (d) real functions (e) thermodynamic functions. Ans: b 45. Which of the following quantities is not the property of the system (a) pressure (b) temperature (c) specific volume (d) heat (e) density. Ans: d 46. According to Avogadro's law, for a given pressure and temperature, each molecule of a gas (a) occupies volume proportional to its molecular weight (b) occupies volume proportional to its specific weight (c) occupies volume inversely proportional to its molecular weight (d) occupies volume inversely proportional to its specific weight (e) occupies same volume. Ans: e 47. Mixture of ice and water form a (a) closed system (b) open system (c) isolated system (d) heterogeneous system (e) thermodynamic system. Ans: d 48. Which of the following is the property of a system Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (a) pressure and temperature (b) internal energy (c) volume and density (d) enthalpy and entropy (e) all of the above. Ans: e 49. On weight basis, air contains following parts of oxygen (a) 21 (b) 23 (c) 25 (d) 73 (e) 79. Ans: b 50. Which of the following is not the intensive property (a) pressure (b) temperature (c) density (d) heat (e) specific volume. Ans: d 51. Which of the following items is not a path function (a) heat (b) work (c) kinetic energy (d) vdp (e) thermal conductivity. Ans: e 52. Work done in an adiabatic process between a given pair of end states depends on (a) the end states only (b) particular adiabatic process (c) the value of index n (d) the value of heattransferred (e) mass of the system. Ans: a 53. Heat and work are (a) point functions (b) system properties (c) path functions (d) intensive properties (e) extensive properties. Ans: c 54. Which of the following parameters is constant for a mole for most of the gases at a given temperature and pressure (a) enthalpy Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) volume (c) mass (d) entropy (e) specific volume. Ans: b 55. The value of n = 1 in the polytropic process indicates it to be (a) reversible process (b) isothermal process (c) adiabatic process (d) irreversible process (e) free expansion process. Ans: b 56. Solids and liquids have (a) one value of specific heat (ft) two values of specific heat (c) three values of specific heat (d) no value of specific heat (e) one value under some conditions and two values under other conditions. Ans: a 57. A perfect gas at 27°C is heated at constant pressure till its volume is double. The final temperature is (a) 54°C (b) 327°C (c) 108°C (d) 654°C (e) 600°C Ans: b 58. Curve A in Fig. 1.1 compared to curves B and C shows the following type of expansion (a) pV"=C (b) isothermal (c) adiabatic (d) free expansion (e) throttling. Ans: b 59. If value of n is infinitely large in a polytropic process pV" = C, then the process is known as constant (a) volume (b) pressure (c) temperature (d) enthalpy (e) entropy. Ans: a 60. The index of compression n tends to reach ratio of specific heats y when (a) flow is uniform and steady Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) process is isentropic (c) process is isothermal (d) process is isentropic and specific heat does not change with temperature (e) process is isentropic and specific heat changes with temperature. Ans: d 61. Change in enthalpy of a system is the heat supplied at (a) constant pressure (b) constant temperature (c) constant volume (d) constant entropy (e) N.T.P. condition. Ans: a 62. The term N.T.P. stands for (a) nominal temperature and pressure (b) natural temperature and pressure (c) normal temperature and pressure (d) normal thermodynamic practice (e) normal thermodynamic pressure. Ans: c 63. A heat exchange process in which the product of pressure and volume remains constant is known as (a) heat exchange process (b) throttling process (c) isentropic process (d) adiabatic process (e) hyperbolic process. Ans: e 64. In an isothermal process, the internal energy of gas molecules (a) increases (b) decreases (c) remains constant (d) may increase/decrease depending on the properties of gas (e) shows unpredictable behaviour. Ans: c 65. Zeroth law of thermodynamics (a) deals with conversion of mass and energy (b) deals with reversibility and irreversibility of process (c) states that if two systems are both in equilibrium with a third system, they are in thermal equilibrium with each other (d) deals with heat engines (e) does not exist. Ans: c 66. If a certain amount of dry ice is mixed with same amount of water at 80°C, the final temperature of mixture will be Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (a) 80°C (b) 0°C (c) 40°C (d) 20°C (e) 60°C. Ans: b 67. The basis for measuring thermodynamic property of temperature is given by (a) zeroth law of thermodynamics (b) first law of thermodynamics (c) second law of thermodynamics (d) third law of thermodynamics (e) Avogadro's hypothesis. Ans: a 68. One watt is equal to (a) 1 Nm/s (b) 1 N/mt (c) 1 Nm/hr (d) 1 kNm/hr (e) 1 kNm/mt. Ans: a 69. Work done is zero for the following process (a) constant volume (b) free expansion (c) throttling (d) all Of the above (e) none of the above. Ans: d 70. For which of the following substances, the gas laws can be used with minimum error (a) dry steam (b) wet steam (c) saturated steam (d) superheated steam (e) steam at atmospheric pressure. Ans: d 71. In a non-flow reversible process for which p = (- 3V+ 15) x 105N/m2,V changes from 1 m to 2 m3. The work done will be about (a) 100 xlOO5 joules (b) lxlO5 joules (c) 10 xlO5 joules (d) 10 xlO5 kilo joules (e) 10xl04ki\ojoules. Ans: c 72. The value of the product of molecular weight and the gas characteristic constant Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR for all the gases in M.K.S. unit is (a) 29.27 kgfm/mol°K (b) 8314kgfm/mol°K (c) 848kgfm/mol°K (d) 427kgfm/mol°K (e) 735 kgfm/mol°K. Ans: c 73. On volume basis, air contains following parts of oxygen (a) 21 (b) 23 (c) 25 (d) 77 (e) 79. Ans: a 74. Universal gas constant is defined as equal to product of the molecular weight of the gas and (a) specific heat at constant pressure (b) specific heat at constant volume (c) ratio of two specific heats (d) gas constant (e) unity. Ans: d 75. The value of the product of molecular weight and the gas characteristic constant for all the gases in S.I. units is (a) 29.27 J/kmol°K (b) 83.14J/kmol°K (c) 848J/kmol°K (d) All J/kmol °K (e) 735 J/kmol °K. Ans: b 76. For which of the following substances, the internal energy and enthalpy are the functions of temperature only (a) any gas (b) saturated steam (c) water (d) perfect gas (e) superheated steam. Ans: d 77. In a free expansion process (a) work done is zero (b) heat transfer is zero (c) both (a) and (b) above (d) work done is zero but heat increases (e) work done is zero but heat decreases. Ans: c Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 78. If a gas vapour is allowed to expand through a very minute aperture, then such a process is known as (a) free expansion (b) hyperbolic expansion (c) adiabatic expansion (d) parabolic expansion (e) throttling. Ans: e 79. The specific heat of air increases with increase in (a) temperature (b) pressure (c) both pressure and temperature (d) variation of its constituents (e) air flow Ans: a 80. If a fluid expands suddenly into vacuum through an orifice of large dimension, then such a process is called (a) free expansion (b) hyperbolic expansion (c) adiabatic expansion (d) parabolic expansion (e) throttling. Ans: a 81. Which of the following processes are thermodynamically reversible (a) throttling (b) free expansion (c) constant volume and constant pressure (d) hyperbolic and pV = C (e) isothermal and adiabatic. Ans: e 82. Which of the following processes is irreversible process (a) isothermal (b) adiabatic (c) throttling (d) all of the above (e) none of the above. Ans: c 83. In order that a cycle be reversible, following must be satisfied (a) free expansion or friction resisted expansion/compression process should not be encountered (b) when heat is being absorbed, temperature of hot source and working sub¬stance should be same (c) when beat is being rejected, temperature of cold source and working sub-stance should be same Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (d) all of the above (e) none of the above. Ans: d 84. For a thermodynamic process to be reversible, the temperature difference between hot body and working substance should be (a) zero (b) minimum (d) maximum (d) infinity (e) there is no such criterion. Ans: a 85. Minimum work in compressor is possible when the value of adiabatic index n is equal to (a) 0.75 (b) 1 (c) 1.27 (d) 1.35 (e) 2. Ans: b 86. Molecular volume of any perfect gas at 600 x 103 N/m2 and 27°C will be (a) 4.17m3/kgmol (b) 400 m3/kg mol (c) 0.15 m3/kg mol (d) 41.7 m3/kg mol (e) 417m3/kgmol. Ans: a 87. A gas is compressed in a cylinder by a movable piston to a volume one-half its original volume. During the process 300 kJ heat left the gas and internal energy remained same. The work done on gas in Nm will be (a) 300 Nm (b) 300,000 Nm (c) 30 Nm (d) 3000 Nm (e) 30,000 Nm. Ans: b 88. The more effective way of increasing efficiency of Carnot engine is to (a) increase higher temperature (b) decrease higher temperature (c) increase lower temperature (d) decrease lower temperature (e) keep lower temperature constant. Ans: d 89. Entropy change depends on (a) heat transfer Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) mass transfer (c) change of temperature (d) thermodynamic state (e) change of pressure and volume. Ans: a 90. For reversible adiabatic process, change in entropy is (a) maximum (b) minimum (c) zero (d) unpredictable (e) negative. Ans: c 91. Isochoric process is one in which (a) free expansion takes place (b) very little mechanical work is done by the system (c) no mechanical work is done by the system (d) all parameters remain constant (e) mass and energy transfer do not take place. Ans: c 92. According to first law of thermodynamics (a) work done by a system is equal to heat transferred by the system (b) total internal energy of a system during a process remains constant (c) internal energy, enthalpy and entropy during a process remain constant (d) total energy of a system remains constant (e) entropy of a system remains constant. Ans: d 93. Energy can neither be created nor destroyed but can be converted from one form to other is inferred from (a) zeroth low of thermodynamic (b) first law of thermodynamics (c) second law to thermodynamics (d) basic law of thermodynamics (e) claussius statement. Ans: b 94. First law of thermodynamics furnishes the relationship between (a) heat and work (b) heat, work and properties of the system (c) various properties of the system (d) various thermodynamic processes (e) heat and internal energy. Ans: b 95. Change in enthalpy in a closed system is equal to heat transferred if the reversible process takes place at constant (a) pressure Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) temperature (c) volume (d) internal energy (e) entropy. Ans: a 96. In an isothermal process, the internal energy (a) increases (b) decreases (c) remains constant (d) first increases and then decreases (e) first decreases and then increases. Ans: c 97. Change in internal energy in a closed system is equal to heat transferred if the reversible process takes place at constant (a) pressure (b) temperature (c) volume (d) internal energy (e) entropy. Ans: c 98. According to first law of thermodynamics (a) mass and energy are mutually convertible (b) Carnot engine is most efficient (c) heat and work are mutually convertible (d) mass and light are mutually convertible (e) heat flows from hot substance to cold substance. Ans: c 99. Total heat of a substance is also known as (a) internal energy (b) entropy (c) thermal capacity (d) enthalpy (e) thermal conductance. Ans: d 100. First law of thermodynamics (a) enables to determine change in internal energy of the system (b) does not help to predict whether the system will or not undergo a change (c) does not enable to determine change in entropy (d) provides relationship between heat, work and internal energy (e) all of the above. Ans: e 101. Addition of heat at constant pressure to a gas results in (a) raising its temperature (b) raising its pressure Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) raising its volume (d) raising its temperature and doing external work (e) doing external work. Ans: d 102. Carnot cycle has maximum efficiency for (a) reversible engine (b) irreversible engine (c) new engine (d) petrol engine (e) diesel engine. Ans: a 103. Measurement of temperature is based on (a) thermodynamic properties (b) zeroth law of thermodynamics (c) first law of thermodynamics (d) second law of thermodynamics (e) joule's law. Ans: b 104. Carnot cycle efficiency depends upon (a) properties of the medium/substance used (b) condition of engine (c) working condition (d) temperature range of operation (e) effectiveness of insulating material around the engine. Ans: d 105. Carnot cycle efficiency is maximum when (a) initial temperature is 0°K (b) final temperature is 0°K (c) difference between initial and final temperature is 0°K (d) final temperature is 0°C (e) initial temperature is minimum possible. Ans: b 106. An engine operates between temperatures of 900°Kandr2 and another engine between T2 and 400°K For both to do equal work, value of T2 will be (a) 650°K (b) 600°K (c) 625°K (d) 700°K (e) 750°K. Ans: a 107. If heat be exchanged in a reversible manner, which of the following property of the working substance will change accordingly (a) temperature (b) enthalpy Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) internal energy (d) entropy (e) all of the above. Ans: d 108. If a system after undergoing a series of processes, returns to the initial state then (a) process is thermodynamically in equilibrium (b) process is executed in closed system cycle (c) its entropy will change due to irreversibility (d) sum of heat and work transfer will be zero (e) no work will be done by the system. Ans: d 109. Which of the following represents the perpetual motion of the first kind (a) engine with 100% thermal efficiency (b) a fully reversible engine (c) transfer of heat energy from low temperature source to high temperature source (d) a machine that continuously creates its own energy (e) production of energy by temperature differential in sea water at different levels. Ans: 110. An actual engine is to be designed having same efficiency as the Carnot cycle. Such a proposition is (a) feasible (b) impossible (c) possible (d) possible, but with lot of sophistications (e) desirable. Ans: d 112. A manufacturer claims to have a heat engine capable of developing 20 h.p. by receiving heat input of 400 kcal/mt and working between the temperature limits of 227° C and 27° C. His claim is (a) justified (b) not possible (c) may be possible with lot of sophistications (d) cost will be very high (e) theroretically possible. Ans: b 113. In a Carnot cycle, heat is transferred at (a) constant pressure (b) constant volume (c) constant temperature (d) constant enthaply (e) any one of the above. Ans: c 114. A diathermic wall is one which (a) prevents thermal interaction Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) permits thermal interaction (c) encourages thermal interaction (d) discourages thermal interaction (e) does not exist. Ans: b 115. An adiabatic wall is one which (a) prevents thermal interaction (b) permits thermal interaction (c) encourages thermal interaction (d) discourages thermal interaction (e) dos not exist. Ans: a 116. The door of a running refrigerator inside a room was left open. Which of the following statements is correct? (a) The room will be cooled to the temperature inside the refrigerator. (b) The room will be cooled very slightly. (c) The room will be gradually warmed up. (d) The temperature of the air in room will remain unaffected. (e) any one of above is possible depending on the capacity. Ans: c 117. Compressed air coming out from a punctured football (a) becomes hotter (b) becomes cooler1 (c) remains at the same temperature (d) may become hotter or cooler depend-ing upon the humidity of the surround¬ing air (e) attains atmospheric temperature. Ans: b 118. Water contained in a beaker can be made to boil by passing steam through it (a) at atmospheric pressure (b) at a pressure below the firuosphejric pressure (c) at a pressure greater than atmospheric pressure (d) any pressure (e) not possible. Ans: c 119. During throttling process (a) heat exchange does not take place (b) no work is done by expanding steam (c) there is no change of internal energy of steam (d) all of the above (e) entropy decreases. Ans: d 120. The energy of molecular motion appears as (a) heat Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) potential energy (c) surface tension (d) friction (e) increase in pressure. Ans: a 121. A sudden fall in the barometer reading is a sign of approaching (a) fine weather (b) rains (c) storm (d) cold wave (e) hot wave. Ans: c 122. The unit'of universal gas constant is (a) watts/°K (b) dynes/°C (c) ergscm/°K (d)erg/°K (e) none of the above. Ans: d 123. Calorie is a measure of (a) specific heat (b) quantity of heat (c) thermal capacity (d)entropy (e) work. Ans: b 124. I kgf/cm2 is equal to (a) 760 mm Hg (b) zero mm Hg (c) 735.6 mm Hg (d) 1 mm Hg (e) lOOmmHg. Ans: c 125. Barometric pressure is equal to (a) 760 mm Hg (b) zero mm Hg (c) 735.6 mm Hg (d) 1 mm Hg (e) 100mm Hg. Ans: a 126. One barometric pressure or 1 atmospheric pressure is equal to (a) 1 kgf/cnr2 (b) 1.033 kgf/cm2 Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) 0 kgf/cm2 (d) 1.0197 kgf/cm2 (e) 100 kgf/cm2. Ans: b 127. The first law of thermodynamics is the law of (a) conservation of mass (b) conservation of energy (c) conservation of momentum (d) conservation of heat (e) conservation of temperature. Ans: b 128. A perpetual motion machine is (a) a thermodynamic machine (b) a non-thermodynamic machine (c) a hypothetical machine (d) a hypothetical machine whose opera-tion would violate the laws of thermodynamics (e) an inefficient machine. Ans: d 129. Kelvin Planck's law deals with (a) conservation of heat (b) conservation of work (c) conversion of heat into work (d) conversion fo work into heat (e) conservation of mass. Ans: c 130. According to Clausis statement of second law of thermodynamics (a) heat can't be transferred from low temperature source to high temperature source (b) heat can be transferred for low temperature to high temperature source by using refrigeration cycle. (c) heat can be transferred from low temperature to high temperature source if COP of process is more than unity (d) heat can't be transferred from low temperature to high temperature source without the aid of external energy (e) all of the above. Ans: d 131. Thermal power plant works on (a) Carnot cycle (b) Joule cycle (d) Rankine cycle (d) Otto cycle (e) Brayton cycle. Ans: c 132. Which of the following is an irreversible cycle Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (a) carnot (b) Stirling (c) ericsson (d) all of the above (e) none of the above. Ans: e 133. Otto cycle consists of following four processes (a) two isothermals and two isentropics (b) two isentropics and two constant volumes (c) two isentropics, one constant volume and one constant pressure (d) two isentropics and two constant pres-sures (e) none of the above. Ans: b 134. The efficiency of a Carnot engine depends on (a) working substance (b) design of engine (c) size of engine (d) type of fuel fired (e) temperatures of source and sink. Ans: e 135. For same compression ratio and for same heat added (a) Otto cycle is more efficient than Diesel cycle (b) Diesel cycle is more efficient than Otto cycle (c) efficiency depends on other factors (d) both Otto and Diesel cycles are equally efficient (e) none of the above. Ans: a 136. The efficiency of Carnot cycle is maximum for (a) gas engine (b) well lubricated engine (c) petrol engine (d) steam engine (e) reversible engine. Ans: e 137. Carnot cycle is (a) a reversible cycle (ft) an irreversible cycle (c) a semi-reversible cycle (d) a quasi static cycle (e) an adiabatic irreversible cycle. Ans: a 138. Diesel cycle consists of following four processes (a) two isothermals and two isentropics (b) two isentropics, and two constant volumes. (c) two isentropics, one constant volume and one constant pressure Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (d) two isentropics and two constant pressures (e) none of the above. Ans: c 139. If both Stirling and Carnot cycles operate within the same temperature limits, then efficiency of Stirling cycle as compared to Carnot cycle (a) more (b) less (c) equal (d) depends on other factors (e) none of the above. Ans: c 140. Stirling and Ericsson cycles are (a) reversible cycles (b) irreversible cycles (c) quasi-static cycles (d) semi-reversible cycles (e) adiabatic irreversible cycles. Ans: a 141. A cycle consisting of two adiabatics and two constant pressure processes is known as (a) Otto cycle (b) Ericsson cycle (c) Joule cycle (d) Stirling cycle (e) Atkinson cycle. Ans: c 142. Reversed joule cycle is called (a) Carnot cycle (b) Rankine cycle (c) Brayton cycle (d) Bell Coleman cycle (e) Dual cycle. Ans: c 143. Brayton cycle consists' of following four processes (a) two isothermals and two isentropics (b) two isentropics and two constant volumes (c) two isentropics, one constant volume and one constant pressure (d) two isentropics and two constant pres-sures (e) none of the above. Ans: d 144. Which of the following cycles is not a reversible cycle (a) Carnot (b) Ericsson (c) Stirling Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (d) Joule (e) none of the above. Ans: e 145. The cycle in which heat is supplied at constant volume and rejected at constant pressure is known as (a) Dual combustion cycle (b) Diesel cycle (c) Atkinson cycle (d) Rankine cycle (e) Stirling cycle. Ans: c 146. The efficiency of Diesei cycle with decrease in cut off (a) increases (b) decreases (c) remains unaffected (d) first increases and then decreases (e) first decreases and then increases. Ans: a 147. Which of the following cycles has maximum efficiency (a) Rankine (b) Stirling (c) Carnot (d) Brayton (e) Joule. Ans: c 148. The ideal efficiency of a Brayton cycle without regeneration with increase ni pressure ratio will (a) increase (b) decrease (c) remain unchanged (d) increase/decrease depending on application (e) unpredictable. Ans: a 149. The ideal efficiency of a Brayton cycle with regeneration, with increase in pressure ratio will (a) increase (b) decrease (c) remain unchanged (d) increase/decrease depending on ap-plication (e) unpredictable. " Ans: b 150. The following cycle is used for air craft refrigeration (a) Brayton cycle (b) Joule cycle Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) Carnot cycle (d) Bell-Coleman cycle (e) Reversed-Brayton cycle. Ans: e 151. Gas turbine cycle consists of (a) two isothermals and two isentropics (b) two isentropics and two constant volumes (c) two isentropics, one constant volume and one constant pressure (d) two isentropics and two constant pressures (e) none of the above. Ans: d 152. The thermodynamic difference between a Rankine cycle working with saturated steam and the Carnot cycle is that (a) carnot cycle can't work with saturated steam (b) heat is supplied to water at temperature below the maximum temperature of the cycle (c) a rankine cycle receives heat at two places (d) rankine cycle is hypothetical (e) none of the above. Ans: b 250 TOP I.C. Engines - Mechanical Engineering Multiple choice Questions and Answers List I.C. Engines Questions and Answers pdf free download 1. The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft (a) 1/2 (b) 1 (c) 2 (d) 4 (e) 8. Ans: c 2. In a diesel engine, the fuel is ignited by (a) spark (b) injected fuel (c) heat resulting from compressing air that is supplied for combustion (d) ignition (e) combustion chamber. Ans: c 3. Scavenging air in diesel engine means (a) air used for combustion sent under pres-sure Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) forced air for cooling cylinder (c) burnt air containing products of combustion (d) air used for forcing burnt gases out of engine's cylinder during the exhaust period (e) air fuel mixture. Ans: d 4. Supercharging is the process of (a) supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere (b) providing forced cooling air (c) injecting excess fuel for raising more load (d) supplying compressed air to remove combustion products fully (e) raising exhaust pressure. Ans: a 5. Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged ? (a) yes (b) no (c) to some extent (d) unpredictable (e) depends on other factors. Ans: b 6. The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called (a) net efficiency (b) efficiency ratio (c) relative efficiency (d) overall efficiency (e) cycle efficiency. Ans: c 7. Compression ratio of LC. engines is (a) the ratio of volumes of air in cylinder before compression stroke and after compression stroke (b) volume displaced by piston per stroke and clearance volume in cylinder (c) ratio of pressure after compression and before compression (d) swept volume/cylinder volume (e) cylinder volume/swept volume. Ans: a 8. The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is (a) same (b) less (c) more (d) more or less depending on power rating (e) unpredictable. Ans: c Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 9. The calorific value of gaseous fuels is expressed in terms of (a) kcal (b) kcal/kg (c) kcal/m2 (d) kcal/n? (e) all of the above. Ans: d 11. If the intake air temperature of I.C. engine increases, its efficiency will (a) increase (b) decrease (c) remain same (d) unpredictable (e) depend on other factors. Ans: b 12. All heat engines utilize (a) low heat value of oil (b) high heat value of oil (c) net claorific value of oil (d) calorific value of fuel (e) all of the above. Ans: a 13. An engine indicator is used to determine the following (a) speed (b) temperature (c) volume of cylinder (d) m.e.p. and I.H.P. (e) BHP. Ans: d 14. Fuel oil consumption guarantees for I.C. engine are usually based on (a) low heat value of oil (b) high heat value of oil (c) net calorific value of oil (d) calorific value of fuel (e) all of the above. Ans: b 17. If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the %age increase in efficiency will be (a) 2% (b) 4% (c) 8% (d) 14% (e) 27%. Ans: d Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 18. In case of gas turbines, the gaseous fuel consumption guarantees are based on (a) high heat value (b) low heat value (c) net calorific value (d) middle heat value (e) calorific value. Ans: b 19. In a typical medium speed 4-stroke cycle diesel engine the inlet valve (a) opens at 20° before top dead center and closes at 35° after the bottom dead center (b) opens at top dead center and closes at bottom dead center (c) opens at 10° after top dead center and closes 20° before the bottom dead center (d) may open or close anywhere (e) remains open for 200°. Ans: a 20. The pressure and temperature at the end of compression stroke in a petrol engine are of the order of (a) 4 - 6 kg/cm2 and 200 - 250°C (b) 6 - 12 kg/cm2 and 250 - 350°C (c) 12 - 20 kg/cm2 and 350 - 450°C (d) 20 - 30 kg/cm2 and 450 - 500°C (e) 30 - 40 kg/cm2 and 500 - 700°C. Ans: b 21. The pressure at the end of compression in the case of diesel engine is of the order of (a) 6 kg/cm (b) 12kg/cmz (c) 20 kg/cmz (d) 27.5 kg/cmz (e) 35 kg/cm Ans: e 22. The maximum temperature in the I.C. engine cylinder is of the order of (a) 500- 1000°C (b) 1000- 1500°C (c) 1500-2000°C (d) 2000-2500°C (e) 2500-3000°C Ans: d 23. The thermal efficiecny of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will (a) increase (b) decrease (c) be independent (d) may increase or decrease depending on other factors (e) none of the above. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR Ans: b 24. Pick up the wrong statement (a) 2-stroke engine can run in any direction (b) In 4-stroke engine, a power stroke is obtained in 4-strokes (c) thermal efficiency of 4-stroke engine is more due to positive scavenging (d) petrol engines work on otto cycle (e) petrol engines occupy more space than diesel engines for same power output. Ans: e 25. Combustion in compression ignition engines is (a) homogeneous (b) heterogeneous (c) both (a) and (b) (d) laminar (e) turbulent. Ans: b 26. The fuel in diesel engine is normally injected at pressure of (a) 5-10 kg/cm2 (b) 20-25 kg/cm2 (c) 60-80 kg/cm2 (d) 90-130 kg/cm2 (e) 150-250 kg/cm2 Ans: d 27. The specific fuel consumption per BHP hour for diesel engine is approximately (a) 0.15 kg (b) 0.2 kg (c) 0.25 kg (d) 0.3 kg (e) 0.35 kg. Ans: b 28. The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed (a) 80°C (b) 120°C (c) 180°C (d) 240°C (e) 320°C. Ans: c 30. Crankcase explosion in I.C. engines usuall occurs as (a) first a mild explosion followed by a bi explosion (b) first a big explosion followed by a mil explosion (c) both mild and big explosions occi simultaneously (d) never occurs (e) unpredictable. Ans: a Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 31. Compression loss in I.C engines occurs duto (a) leaking piston rings (b) use of thick head gasket (c) clogged air-inlet slots (d) increase in clearance volume caused b bearing-bushing wear (e) all of the above. Ans: e 32. The specific fuel consumption per BH hour for a petrol engine is approximately (a) 0.15 kg (b) 0.2 kg (c) 0.25 kg (d) 0.3kg (e) 0.35 kg. Ans: c 33. The air requirement of a petrol engine during starting compared to theoretical airequired for complete combustion is (a) more (b) loss (c) same (d) may be more or less depending on engine capacity (e) unpredictable. Ans: b 34. The inlet value of a four stroke cycle I.C engine remains open for nearly (a) 180° (b) 125° (c) 235° (d) 200° (e) 275°. Ans: c 35. Which of the following is not an interns combustion engine (a) 2-stroke petrol engine (b) 4-stroke petrol engine (c) diesel engine (d) gas turbine (e) steam turbine. Ans: e 36. Pick up the false statement (a) Thermal efficiency of diesel engine i about 34% (b) Theoretically correct mixture of air am petrol is approximately 15 : 1 (c) High speed compression engines operate on dual combustion cycle (d) Diesel engines are compression ignition engines (e) S.I. engines are quality-governed engines. Ans: e Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 37. If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the (a) exhaust will be smoky (b) piston rings would stick into piston grooves (c) exhaust temperature will be high (d) engine starts overheating (e) scavenging occurs. Ans: e 38. The output of a diesel engine can be increased without increasing the engine revolution or size in following way (a) feeding more fuel (b) increasing flywheel size (c) heating incoming air (d) scavenging (e) supercharging. Ans: e 39. It the temperature of intake air in IC engines is lowered, then its efficiency will (a) increase (b) decrease (c) remain same (d) increase upto certain limit and then decrease (e) decrease upto certain limit and then in-crease. Ans: a 40. In a typical medium speed 4-stroke cycle diesel engine (a) compression starts at 35° after bottom dead center and ends at top dead center (b) compression starts at bottom dead center and ends at top dead center (c) compression starts at 10° before bottom dead center and, ends just before top dead center (d) may start and end anywhere (e) none of the above. Ans: a 41. For the same compression ratio (a) Otto cycle is more efficient than the Diesel (b) Diesel cycle is more efficient'than Otto (c) both Otto and Diesel cycles are, equally efficient (d) compression ratio has nothing to do with efficiency (e) which is more efficient would depend on engine capacity. Ans: a 42. The precess of breaking up or a lipuid into fine droplets by spraying is called (a) vaporisation (b) carburetion (c) ionisation (d) injection (e) atomisation. Ans: e Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 43. As a result of detonation in an I.C. engine, following parameter attains very high value (a) peak pressure (b) rate of rise of pressure (c) rate of rise of temperature (d) peak temperature (e) rate of rise of horse-power. Ans: b 44. Which of the following statements is correct? (a) All the irreversible engines have same efficiency (b) All the reversible engines have same efficiency (c) Both Rankine and Caront cycles have same efficiency between same temperature limits (d) All reversible engines working between same temperature limits have same- efficiency (e) Between same temperature limits, both petrol and diesel engines have same efficiency. Ans: d 45. Most high speed compression engines operate on (a) Diesel cycle (b) Otto cycle (c) Dual combustion cycle (d) Special type of air cycle (e) Carnot cycle. Ans: c 48. The accunmulation of carbon in a cylinder results in increase of (a) clearance volume (b) volumetric efficiency (c) ignition time (d) effective compression ratio (e) valve travel time. Ans: d 49. Which of the following medium is compressed in a Diesel engine cylinder (a) air aione (b) air and fuel (c) air and lub oil (d) fuel alone (e) air, fuel and lub oil. Ans: a 54. The air-fuel ratio of the petrol engine is controlled by (a) fuel pump (b) governor (c) injector (d) carburettor Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (e) scavenging. Ans: d 55. In a typical medium speed, 4-stroke cycle diesel engine (a) fuelinjection starts at 10° before to dead center and ends at 20° after tor dead center (b) fuel injection starts at top dead center and ends at 20° after top dead center (c) fuel injection starts at just before top dead center and ends just after top deac center (d) may start and end anywhere (e) none of the above. Ans: a 56. Diesel fuel, compared to petrol is (a) less difficult to ignite (b) just about the same difficult to ignite (c) more difficult to ignite (d) highly ignitable (e) none of the above. Ans: c 57. In diesel engine the diesel fuel injected into cylinder would burn instantly at about compressed air temperature of (a) 250°C (b) 500°C (c) 1000°C (d) 150CPC (e) 2000°C. Ans: c 58. When crude oil is heated, then which of the following hydrocarbon is given off first. (a) kerosene (b) gasoline (c) paraffin (d) diesel (e) natural gas. Ans: e 59. The rating of a diesel engine, with increase in airintlet temperature, will (a) increase linearly (b) decrease linearly (c) increase parabolically (d) decrease parabolically (e) first decrease linearly and then increase parabolically. Ans: b 60. A 75 cc engine has following parameter as 75 cc (a) fuel tank capacity (b) lub oil capacity (c) swept volume Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (d) cylinder volume (e) clearance volume. Ans: c 61. A heat engine utilises the (a) calorific value of oil (b) low heat value of (c) high heat value of oil (d) mean heat value of oil (e) all of the above. Ans: c 62. Gaseous-fuel guarantees are based on (a) calorific value of oil (b) low heat value of oil (c) high heat value of oil (d) mean heat value of oil (e) all of the above. Ans: b 63. Fuel consumption of diesef engines is not guaranteed at one quarter load because at such low loads (a) the friction is high (b) the friction is unpredictable (c) the small difference in cooling water temperature or in internal friction has a disproportionate effect (d) the engine is rarely operated (e) none of the above. Ans: c 64. Polymerisation is a chemical process in which molecules of a compound become (a) larger (b) slowed down (c) smaller (d) liquid (e) gaseous. Ans: a 65. The term scavenging is generally associated with (a) 2-stroke cycle engines (b) 4-stroke cycle engines (c) aeroplane engines (d) diesel engines (e) high efficiency engines. Ans: e 66. In diesel engine, the compression ratio in comparison to expansion ratio is (a) same (b) less (G) more Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (d) variable (e) more/less depending on engine capacity. Ans: c 67. The cam shaft of a four stroke I.C. engine running at 1500 rmp will run at (a) 1500 rpm (b) 750 rpm (c) 3000 rpm (d) any value independent of engine speed (e) none of the above. Ans: b 68. Engine pistons 'are usually made of aluminium alloy because it (a) is lighter (b) wears less (c) absorbs shocks (d) is stronger (e) does not react with fuel and lub oil. Ans: a 69. Most high speed compression engines operate on (a) Otto cycle (b) Diesel cycle (c) Dual cycle (d) Carnot cycle (e) Two stroke cycle. Ans: c 70. The specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is (a) same (b) more (c) less (d) less or more depending on operating conditions (e) unpredictable. Ans: b 71. A diesel engine as compared to petrol engine (both running ar rated load) is (a) more efficient (b) less efficient (c) equally efficient (d) unperdictable (e) other factors will decide it. Ans: a 72. The size of inlet valve of.an engine in comparison to exhaust valve is (a) more (b) less (c) same (d) more/less depending on capacity of engine Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (e) varies from design to design. Ans: b 74. In a cycle, the spark lasts roughly for (a) 1 sec (b) 0.1 sec (c) 0.01 sec (d) 0.001 sec (e) 0.0001 sec. Ans: d 75. Which of the following is false statement : Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following (a) piston ring and cylinder wear (b) formation of hard coating on piston skirts (c) oil sludge in the engine crank case (d) detonation (e) forms corrosive acids. Ans: d 76. Which of the following is false statement. Some of the methods used to reduce diesel smoke are as follows (a) using additives in the fuel (b) engine derating i.e. reducing the maxi-mum flow of fuel (c) increasing the compression ratio (d) adherence to proper fuel specification (e) avoidance of overloading. Ans: c 77. The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be (a) higher (b) lower (c) remain unaffected (d) unpredictable (e) none of the above. Ans: a 78. Pick up the wrong statement about supercharging (a) supercharging reduces knocking in diesel engines (b) there can be limited supercharging in petrol engines because of detonation (c) supercharging at high altitudes is essential (d) supercharging results in fuel economy (e) supercharging is essential in aircraft engines. Ans: d 79. The actual volume of fresh charge admitted in 4-stroke petrol engine is (a) equal to stroke volume (b) equal to stroke volume and clearance volume Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) less than stroke volume (d) more than stroke volume (e) more than cylinder volume. Ans: c 80. The magneto in an automobile is basically (c) transformer (b) d.c. generator (c) capacitor (d) magnetic circuit (e) a.c. generator. Ans: b 81. The reason for supercharging in any engine is to (a) increase efficiency (b) increase power (c) reduce weight and bulk for a given out-put (d) effect fuel economy (e) none of the above. Ans: c 82. The operation of forcing additional air under pressure in the engine cylinder is known as (a) scavenging (b) turbulence (c) supercharging (d) pre-ignition (e) dissociation and carburretion of fuel. Ans: c 83. Supercharging is essential in (a) diesel engines (b) gas turbines (c) petrol engines (d) aircraft engines (e) marine engines. Ans: d 84. The minimum cranking speed in case of petrol engine is about (a) half the operating speed (b) one-fourth of operating speed (c) 250-300 rpm (d) 60-80 rpm (e) 10-20 rpm Ans: d 85. In a typical medium speed 4 stroke cycle diesel engine (a) exhaust valve opens at 35° before bot-tom dead center and closes at 20° after top dead center (b) exhaust valve opens at bottom 'dead center and closes at top dead center Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) exhaust valve opens just after bottom dead center and closes just before top dead center (d) may open and close anywhere (e) none of the above is true. Ans: a 86. Flash point of fuel oil is (a) minimum temperature to which1 oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame (b) temperature at which it solidifies or congeals (c) temperature at which it catches fire without external aid (d) indicated by 90% distillation temperature, i.e. when 90% of sample oil has distilled off (e) none of the above. Ans: a 87. The mean effective pressure obtained from engine indicator indicates the (a) maximum pressure developed (b) minimum pressure (c) instantaneous pressure at any instant (d) exhaust pressure (e) average pressure. Ans: e 88. For the same power developed in I.C. engines, the cheaper system is (a) naturally aspirated (b) supercharged (c) centrifugal pump (d) turbo charger (e) none of the above. Ans: b 89. Installation of supercharger on a four-cycle diesel engine can result in the following percentage increase in power (a) upto 25% (b) upto 35% (c) upto 50% (d) upto 75% (e) upto 100%. Ans: e 90. Scavenging is usually done to increase (a) thermal efficiency (b) speed (c) power output (d) fuel consumption (e) all of the above. Ans: c Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 91. Which of the following is the lightest and most volatile liquid fuel (a) diesel (b) kerosene (c) fuel oil (d) gasoline (e) lub oil. Ans: d 92. The theoretically correct air fuel ratio for petrol engine is of the order of (a) 6 : 1 (b) 9 : 1 (c) 12 : 1 (d) 15 : 1 (e) 20 : 1. Ans: d 93. Air fuel ratio for idling speed of a petrol engine is approximately (a) 1 : 1 (b) 5 : 1 (c) 10:1 (d) 15 : 1 (e) 20 : 1. Ans: c 94. Air fuel ratio at which a petrol engine can not work is (a) 8 : 1 (b) 10 : 1 (c) 15 : 1 (d) 20 : 1 and less (e) will work at all ratios. Ans: d 95. For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of (a) 9 : 1 (b) 12 : 1 (c) 15 : 1 (d) 18 : 1 (e) 20: 1. Ans: b 96. The following volume of air is required for consuming 1 liter of fuel by a four stroke engine (a) 1 m3 (b) 5 m3 (c) 5-6 m3 (d) 9-10 m3 (e) 15-18 m3. Ans: d Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 97. Pour point of fuel oil is the (a) minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame (b) temperature at which it solidifies or congeals (c) it catches fire without external aid (d) indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off (e) temperature at which it flows easily. Ans: b 98. A 5 BHP engine running at full load would consume diesel of the order of (a) 0.3 kg/hr (b) 1 kg/hr (c) 3 kg/hr (d) 5 kg/hr (e) 10 kg/hr. Ans: b 99. Diesel engine can work on very lean air fuel ratio of the order of 30 : 1. A petrol engine can also work on such a lean ratio provided (a) it is properly designed (b) best quality fuel is used (c) can not work as it is impossible (d) flywheel size is proper (e) engine cooling is stopped. Ans: c 100. A diesel engine has (a) 1 valve (b) 2 valves (b) 3 valves (d) 4 valves (e) no valve. Ans: c 101. A hmh flame speed is obtained in diesel engine when air fuel ratio is (a) uniform throughout the mixture (b) chemically correct mixture (c) about 3-5% rich mixture (d) about 10% rich mixture (e) about 10% lean mixture. Ans: d 102. The knock in diesel engine occurs due to (a) instantaneous and rapid burning of the first part of the charge (b) instantaneous atuo iginition of last part of charge (c) delayed burning of the first part of the charge (d) reduction of delay period (e) all ot the above. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR Ans: a 103. The air-fuel ratio in petrol engines-is controlled by (a) controlling valve opening/closing (b) governing (c) injection (d) carburettion (e) scavenging and supercharging. Ans: d 104. Volatility of diesel fuel oil is (a) minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame (b) temperature at which it solidifies or congeals (c) it catches fire without external aid (d) indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off (e) temperature at which it flows easily. Ans: d 105. Which is more viscous lub oil (a) SEA 30 (b) SAE 4£ (c) SAE 50 (d) SAE 70 (e) SAE 80. Ans: e 106. In the opposed piston diesel engine, the combustion chamber is located (a) above the piston (/;) below the piston (c) between the pistons (d) any when (e) there is no such criterion. Ans: c 107. A stoichiometric air-fuel ratio is (a) chemically correct mixture (b) lean mixture (c) rich mixture for idling (d) rich mixture for over loads (e) the ratio used at full rated parameters. Ans: a 108. In a naturally aspirated diesel engine, the air is supplied by (a) a supercharger (b) a centrifugal blower (c) a vacuum chamber (d) an injection tube (e) forced chamber Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR Ans: c 109. In loop scavenging, the top of the piston is (a) flat (b) contoured (c) slanted (d) depressed (e) convex shaped. Ans: b 110. In the crankcase method of scavenging, the air pressure is produced by (a) supercharger (b) centrifugal pump (c) natural aspirator (d) movement of engine piston (e) reciprocating pump. Ans: d 111. In order to prevent formation of carbon on the injector, the temperature of nozzle tip should be (a) less than 100°C (b) between 100-250°C (c) between 250 - 300°C (d) between 400 - 500°C (e) between 500 - 1000°C. 11 The thermal efficiency of a petrol engine of two stroke with crank case scavenging as compared to four stroke petrol engine with same comperssion ratio will be (a) higher (b) lower (c) same (d) depends on size of engine (e) unpredictable. 113. Ignition quailty of petrol is expressed by (a) octane number (b) cetane number (c) calorific value (d) self ignition temperature (e) distillation temperature. 114. Petrol is distilled at a temperature in range of (a) 30 - 65°C (b) 65 - 220°C (c) 220-350°C (d) 350-450°C (e) 450-550°C. 115. Kerosene is distilled at (a) 30 - 65°C Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) 65 - 220°C (c) 220 - 350°C (d) 350 - 450°C (e) 450-550°C. 116. Self-ignition temperature of petrol is of the order of (a) 150°C (b) 240°C (c) 370°C (d) 450°C (e) more than 500°C. 117. Iso-oct ,ne (a) has octane number of 0 (b) has octane number of 50 (c) has octane number of 100 (d) is an index of detonation quality (e) is an index of knocking quality. 118. Octane number is determined by comparing the performance of the petrol with the following hydrocarbons (a) iso-octane (b) mixture of normal heptane and iso-oc-tane (c) alpha methyl napthalene (d) mixture of methane and ethane (e) mixture of paraffins and aromatics. 119. Cetane (a) has zero cetane number (b) has 100 cetane number (c) helps detonation (d) is a straight chain paraffin (e) determines the efficiency of an I.C. engine. 120. Ethyl fluid is used (a) to increase the octane rating of the fuel (b) to increase the cetane rating of the fuel (c) as a defrosting agent (d) as a superior type of fluid compared to others (e) to improve lubricating quality of fuel. 121. The self-ignition temperature of diesel oil compared to petrol is (a) higher (b) lower (c) same (d) depends on quality of fuel (e) unpredictable? 112. Normal heptane (a) accelerates auto-ignition Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) helps to resist auto-ignition (c) does not affect auto-ignition (d) has no relation with auto-ighition (e) retards auto-ignition. 123. Cetane number is determined by comparing the performance of diesel oil with the following hydrocarbons (a) cetane (b) mixture of cetane and alphamethyl napthalene (c) ethylene dibromide (d) mixture of aldehydes and ketones (e) mixture of cetane with tetra-ethyl lead 124. Which is correct statement about reaction time for autoignition of fuel and the fuel air ratio (a) lean mixture has high reaction time (b) rich mixture has high reaction time (c) chemically correct mixture has mini-mum reaction time (d) all of the above. (e) non of the above. 125. Violent sound pulsations within the cylinder of an I.C. engine are caused due to (a) heavy turbulence (b) improved scavenging (c) heavy supercharging (d) detonation (e) preignition. 126. Auto-ignition temperature is (a) minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame (b) temperature at which it solidifies or congeals (c) that at which it catches fire without external aid (d) indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off (e) indicated by 50% distillation temperature. 127. Ignition lag is (a) the time taken by fuel after injection (before top dead center) to reach upto auto- ignition temperature (b) time before actual fuel injection and the pump plunger starts to pump fuel (c) time corresponding to actual injection and top dead center (d) time corresopnding to actual ingition and top dead center (e) none of the above. 128. The spark plug gap is normally maintained at (a) 0.1 to 0.2 mm (b) 0.2 to 0.4 mm (c) 0.45 to 0.6 mm Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (d) 0.6 to 0.8 mm (e) 0.8 to 1 mm. 129. The function of a fuel pump in a petrol pump is to (a) inject fuel in cylinder (b) supply fuel when carburettor fails (c) pump fuel so that it reaches carburettor (to improve thermal efficiency) (d) does not exist. 130. The delay period in petrol engine is of the order of (a) 0.001 sec (b) 0.002 see (c) 0.01 sec (d) 0.05 sec (e) 0.1 sec. 131. Detonation is caused by the following unstable compounds (a) peroxides, aldehydes and ketones (b) peroxides, aldehydes, oxides and sul-phides (c) aldehydes, oxides and ketones (d) ketones and sulphur compounds (e) none of the above. 13 If overhead clearance is less, then the following type of engine should be selected (a) V-type (b) In-line (c) Vertical (d) Horizontal (e) Radial. 133. Which is false statement about advantages of V-type engine (a) compact design requiring lesser space (b) improved distribution of air to cylinder (c) casting less liable to distortion (d) reduced torsional vibration because of shorter crankshaft (e) less overhead clearance. 134. The pistons are usually given a coating such as tin plating in order to (a) reduce weight (b) conduct heat efficiently (c) reduce possibility of scoring (d) reduce friction (e) increase lubrication effect. 135. Piston rings are usually made of (a) cast iron (b) aluminium (c) phosphor bronze (d) babbitt (e) carbon steel. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 136. Piston rings are plated with chromium,cadmium or phosphate in order to (a) reduce cost (b) improve surface finish (c) prevent clogging (d) reduce wear and eliminate scuffing (e) improve heat transfer. 137. The top piston ring nearer to the piston crown is known as (a) compression ring (b) oil ring (c) scrapper ring (d) groove ring (e) leading ring. 138. In order to prevent knock in the S.I. engines, the charge away from the spark plug should have (a) low temperature (b) low density (c) long ignition delay (d) rich mixture (e) all of the above. 139. Diesel engines have low specific fuel consumption compared to petrol engine. This statement is (a) not true (b) true at full load (c) true at part load (d) true at both part and full load (e) there could not be any such criterion. 140. To reduce the possibility of knock in the C.I. engines, the first elements of fuel and air should have (a) high temperature (b) high density (c) short delay (d) reactive mixture (e) all of the above. 141. The detonation tendency in petrol engines for specified conditions of fuel rating, compression ratio, speed etc. can be con-trolled by having (a) smaller cylinder bore (b) bigger cylinder bore (c) medium cylinder bare (d) cylinder bore could be anything as it does not control detonation (e) proper stroke legth. 142. According to Recardo's theory, detonation occurs due to (a) instantaneous auto-ignition of last part of charge to be burnt (b) improper mixing of air and fuel Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) improper combustion (d) self ignition temperature has nothing to do with detonation (e) none of the above. 143. A fuel will detonate less if it has (a) higher self ignition temperature (b) lower self ignition temperature (c) proper self ignition temperature (d) self ingition temperature has nothing to do with detonation (e) none of the above. 144. The knocking in diesel engines for given fuel, will be (a) enhanced by increasing compression ratio (b) enhanced by decreasing compression ratio (c) unaflected by compression ratio (d) first enhanced by increasig compression ratio upto a limit beyond which it will be suppressed (e) dependent on other factors. 145. The ignition of charge by some hot surface in the engine cylinder before operation of spark plug is known as (a) auto ignition (b) preignition / (c) retarded ignition (d) accelerated ignition (e) detonation. 146. Injection lag is (a) the time taken by fuel after injection (before top dead center) to reach upto auto- ignition temperature (b) time before actual fuel injection and the pump pluger starts to pump fuel (c) time corresponding to actual injection and top dead center (d) time corresponding to actual ignition and top dead center (e) none of the above. 147. Ignition quality of diesel-fuel oil is expressed by an index called (a) octane number (b) cetane number (c) calorific value (d) carbon content (e) ignition temperature. 148. For best results of efficient combustion, high speed diesel engines need an approximate cetane number of (a) 100 (b) 10 (c) 50 (d) 5 (e) 1. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 149. Calorific value of diesel oil is of the order of (a) 3000 kcal/kg (b) 5000 kcal/kg (c) 7500 kcal/kg (d) 10000 kcal/kg (e) 15000 kcal/kg. 150. Carbon residue in diesel oil should not be more than (a) 1% (b) 0.5% (c) 0.1% (d) 0.01% (e) 0.001%. 151. The most popular firing order in case of four cylinder in-line I.C. engine is (a) 1-2-3-4 (b) 1-3-2-4 (c) 1-4-2-3 (d) 1-2-4-3 (e) 1-3-4- 15 The compression ratio of motor cars is (a) 5 (b) 1 (c) 10 (d) 13 (e) 16. 153. The specific gravity of diesel oil Is (a) 1 (b) 0.7 (c) 0.85 (d) 0.5 (e) 1.25. 154. Freezing temperature of petrol is usually (a) 0°C (b) - 10°C (c) 10°C (d) less than - 30°C (e) less than - 273°C. 155. The specific gravity of petrol is about (a) 0.65 (b) 0.75 (c) 0.85 (d) 0.95 (e) 1.1. 156. Pick up the correct statement. Detonation can be controlled by Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (a) varying compression ratio (b) using lian mixture (c) retarding the spark timing (d) reducing the r.p.m. (e) increasing inlet pressure. 157. The efficiency of I.C. engines normally is of the order of (a) 15-20% (b) 20-25% (c) 25-30% (d) 30-35% (e) 35-50%. 158. The firing order in a six stroke I.C. engine is (a) 1-3-6-5-2-4 (b) 1-4-2-5-6-3 (c) 1-6-2-5-4-3 (d) 1-5-2-6-3-4 (e) 1-5-3-4-2-6. 159. Sulphur content in diesel oil should not be more than (a) 10% (b) 5% (c) 1% (d) 0.1% (e) 0.01%. 160. The m.e.p. of a diesel cycle having fixed compression ratio with increase in cut-off will (a) increase (b) decreae (c) be unaffected (d) depend on other factors (e) unpredictable. 161. The ash content in diesel oil should bot be more than (a) 1% (b) 5% (c) 0.1% (d) 0.01% (e) 0.001%. 16 The pour point of diesel oil must be (a) lower than the coldest atmospheric temperature at which oil is to be pumped (b) higher than above (c) has no such relation (d) more than 100°C (e) none of the above. 163. High carbon content in diesel oil used for diesel engine leads to Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (a) production of highly corrosive gases corroding the cylinder walls and exhaust system (b) excessive engine wear (c) damaging of both the storage tank and the engine (d) deposition on engine parts (e) none of the above. 164. Exhaust pipes of engines are covered with insulating marterial in order to (a) keep the exhaust pipes warm (b) reduce formation of condenstae (c) reduce heat transfer to the engine room (d) increase engine efficiency (e) conserve heat. 165. Ignition timing of a multicylider petrol engine can be adjusted by (a) rotating the crank (b) adjusting the spark plug gap (c) adjusting ignition coil position (d) rotating the distributor (e) delaying the spark by increasing capacitor in ignition circuit. 166. Fuel consumption with increase in back pressure will (a) increase (b) decrease (c) remain unaffected (d) depend on other factors (e) none of the above. 167. The cooling water requirement for diesel engine is of the order of (a) 0.2 to 1.0 liter per minute per h.p. (b) 1 to 3 liters per minute per h.p. (c) 5 to 10 liters per minute per h.p (d) 10 to 20 liters per minute per h.p. (e) 20-30 liters per minute per h.p. 168. A 4-stroke diesel engine needs about following amount of air (a) 75 cc per min. per h.p. (b) 750 cc per min. per h.p. (c) 7500 cc per min. per h.p. (d) 75000 cc per min. per h.p. (e) 750000 cc per min. per h.p. 169. Leakage past the piston rings and valve seats in I.C. engines with increase in speed (a) increases. (b) decreases (c) remains same (d) unpredictable (e) none of the above. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 170. The heat wasted in diesel engine is of the order of (a) 80% (b) 65% (c) 50% (d) 35% (e ) 25%. 171. With increa.se in speed of vehicle, the back pressure will (a) decrease (b) increase (c) remain unalfected (d) depend on other factors (e) none of the above. 17 The function of a distributor in an automobile is to (a) distribute charge, equally to all the cylinders (b) regulate power (c) feed lub oil to all moving parts (d) time the spark (e) inject fuel at appropriate time. 173. The ratio of useful power; engine friction exhaust gas losses; cooling water, air and oil losses for a diesel engine is of the order of (a) 5:25:30:50 (b) 25:35:5:35 (c) 25:5:10:60 (d) 40:30:15:15 (e) 25:5:35:35. 174. For same power and same speed, the flywheel of a four stroke engine as compared to two-stroke I.C. engine will be (a) smaller (b) bigger (c) same size (d) dependent on other engine parameters (e) unpredictable. 175. Air injection in I.C. engines refers to injection of (a) air only (b) liquid fuel only (c) liquid fuel and air (d) supercharging (e) does not exist. 176. Solid injection in I.C. engines refers to injection of (a) liquid fuel only (b) liquid fuel and air (c) solid fuel (d) solid fuel and air (e) does not exist. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 177. The system of lubrication used for motor cycles and scooters is by (a) forced lubrication system (b) splash lubrication (c) applying grease under pressure (d) wet sump method (e) mixing about 5% lub oil with petrol. 178. The m.e.p. of a petrol engine first increases as the fuel air ratio is increased and then decreases on further increase in fuel air ratio. The m.e.p. is maximum in the zone of (a) lean mixture (b) chemically correct mixture (c) rich mixture (d) unpredictable (e) none of the above. 179. The specific fuel consumption for a petrol engine first decreases with increase in fuel air ratio and then increases with further increase in fuel air ratio. The minimum value occurs in the range of (a) lean mixture (b) chemically correct mixture (c) rich mixture (d) unpredictable (e) none of the above. 180. The thermal efficiency of a two cycle engine as compared to four cycle engine is (a) more (b) less (c) same (d) more upto some load and then less (e) it may be less or more depending on several other factors. 181. Diesel engines as compared to petrol engines require (a) bigger flywheel (b) smaller flywheel (c) same size flywheel (d) no flywheel (e) flywheel whose size may be less or more depending on several other fac-tors. 183. The tendency of a diesel engine to knock increases, if (a) engine speed is increased (b) engine H.P. is increased (c) octane number of fuel is increased (d) conperssion ratio is increased (e) engine has to move uphill. 184. The tendency of a petrol engine to knock increases by (a) supercharging (b) scavenging Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) increasing engine H.P, (d) reducing the spark advance (e) increasing cetane number of fuel. 185. Free acids in diesel oil for diesel engine lead to (a) production of highly corrosive gases corroding the cylinder walls and exhaust system (b) excessive engine wear (c) damaging of both the storage tank and the engine (d) deposition on engine parts (e) excessive fuel consumption. 186. Thermal efficiency of high speed diesel engine at design load may be of the order of (a) 20% (b) 35% (c) 50% (d) 70% (e ) 85%. 187. The thermostat in I.C. engines permitting hot water to go to radiator is set around (a) 70-80°C (b) 80-85°C (c) 85-95°C (d) above 100°C (e) above 120°C. 188. The brake mean effective pressure of an I.C. engine with increase in speed will (a) increase (b) decrease (c) remain unaffected. (d) fluctuate according to engine speed (e) unpredictable. 189. High ash and sediment in diesel oil used in diesel engine lead to (a) production of highly corrosive gases corroding the cylinder walls and ex-haust system (b) excessive engine wear (c) damaging of both the storage tank and the engine (d) deposition on engine parts (e) blocking of exhaust pipes. 190. Mixing of fuel and air in case of dies engine occurs in (a) injection pump (b) injector (c) inlet manifold (d) carburettor (e) engine cylinder. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 191. The advantage of reversing the flow of a in an air cleaner is to (a) increase velocity of air (b) increase air flow (c) reduce the velocity of air (d) throw out a large percentage of foreig matter (e) cool the air. 19 The most effective air cleaner in case diesel engines is (a) dry type (b) wet type (c) whirl type (d) oil bath type (e) all are equally good. 193. Fins are provided over engine cylinder scooters for (a) higher strength of cylinder (b) better cooling (c) good appearance (d) higher efficiency (e) easier handling and ease in manufacturing. 194. The elements of most concern in regard pollution caused by engines are (a) CO and C02 (b) CO and hydrocarbons (c) C02 and hydrocarbons (d) carbon and dust (e) hot products of combustion 195. The preferred location of an oil cooler is (a) before the filters (b) after the filters (c) between the filters (d) before and after the filters (e) any where. 196. The petrol from tank to the automotive ergine is fed by (a) gravity (b) pump run by engine (c) suction pressure created by, suctio stroke (d) capillary action (e) fuel pump. 197. In petrol engine, increase of cooling water temperature will (a) increase the knocking tendency (b) decrease the knocking tendecny (c) not affect the knocking tendency (d) increase or decrease knocking tendency depedning on strength and time of spark (e) unpredictable. 207. In carburettors, the top of the fuel jet with reference to the level in the float Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR chamber is kept at (a) same level (b) slightly higher level (c) slightly lower level (d) may be anywhere (e) varies from situation to situation. 208. Carburretion is done to (a) feed petrol into cylinder (b) govern the engine (c) break up and mix the petrol with air (d) heat up the charge to cylinder (e) scavenge the cylinder. 209. Power impulses from an I.C. engine are somoothed out by (a) governor (b) crank shaft (c) gear box (d) flywheel (e) timing spark properly. 210. The theoretically correct mixture of air and petrol is approximately (a) 8 : 1 (b) 12 : 1 (c) 15 : 1 (d) 20 : 1 (e) 24: 1. 211. For low speed operation or for idling in petrol engines, the engine requirements are for (a) lean mixture (b) theoretically correct mixture (c) rich mixture (d) any type of mixture (e) lean/rich mixture depending upon capacity of engine. 21 In petrol engines, advancing the spark timing will (a) increase the knocking tendency (b) decrease the knocking tendency (c) not affect the knocking tendncy (d) increase or decrease knocking tendency depending on strenght and time of spark (e) unpredictable. 213. The following type of carburettor is preferred (a) concentric type (b) eccentric type (c) horizontal type (d) vertical type (e) none of the above. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 214. In the passanger cars, the following type of carburettor is preferred (a) horizontal type (b) downward draught type (c) upward draught type (c) inclined draught type (e) any one of the above types. 215. The essential equipment for producing high vlotage for sparking in petrol engines with battery is (a) ignition coil (b) ignition coil and distributor (c) ignition coil and condenser (d) ignition coil and contact breaker (e) ignition coil, contact breaker and con-denser. 216. The ignition coil in diesel engines produces voltage of the order of (a) 6 to 12 volts (b) 240 volts (c) 1000 volts (d) 20,000 volts (e) 80,000 volts. 217. If the door of a diesel engine crankcase is opened just after shutdown before cooling of engine, then (a) efficiency of engine will be poor (b) there is a risk of explosion taking place (c) it is the safest practice (d) some parts may be subjected (e) some lub oil may be wasted. 218. The thermal efficiency of a diesel engine is of the order of (a) 92% (b) 68% (c) 52% (d) 34% (e) 25%. 219. The thermal efficiency of a gas engine is of the order of (a) 92% (b) 68% (c) 52% (d) 34% (e) 25%. 220. Theoretically, the following engine should have maximum efficiency (a) gas engine (b) 2-stroke S.I. engine (c) 4-stroke S.I. engine (d) steam engine (e) 4-stroke C.I. engine. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 221. In petrol engine using a fixed octane rating fuel and fixed compression ratio, super charging will (a) increase the knocking tendency (b) decrease the knocking tendency (c) not affect the knocking tendency (d) increase or decrease knocking tendency depending on strength and time of spark (e) unpredictable. 223. High sulphur content in diesel oil used for diesel engines leads to (a) production of highly corrosive gases corroding the cylinder walls and exhaust system (b) excessive engine wear (c) damaging of both the storage tank and the engine (d) deposition on engine parts (e) reduction in thermal efficiency. 224. In open combustion chamber in diesel engines (a) the shape and layout of the piston crown, the inlet port, and the valve produce the turbulent effect on fuel mixture (b) fuel is injected into an auxiliary chamber that is separated from the cylinder by an orifice or throat (c) only a part of air charge is contained in an auxiliary chamber in which the fuel starts to burn with insufficient air which due to explosion tendency mixes thoroughly into main cylinder charge (d) fuel is injected at atmospheric pres¬sure (e) there are no valves. 225. The basic requirement of a good combustion chamber is (a) high compression ratio (b) low compression ratio (c) low volumetric efficiency (d) minimum turbulence (e) high power output and high thermal efficiency. 226. Deposition of carbon in petrol engine cylinder would result in increase of (a) clearance volume (b) swept volume (c) compression ratio (d) volumetric efficiency (e) mean effective pressure. 227. Which of the following engines can work on very lean mixture (a) S.I. engine (b) C.I. engine (c) two stroke engine (d) four stroke engine (e) all of the above. 228. If petrol is used in a diesel engine, then Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (a) higher knocking will occur (b) efficiency will be low (c) low power will be produced (d) black smoke will be produced (e) lot of fuel will remain unburnt. 229. Hot air standard diesel cycle efficiency with increase in value of C„ (a) increases (b) decreases (c) remains unaffected (d) depends on other factors (e) unpredictable. 230. In turbulence chamber in diesel engine (a) the shape and layout of the piston crown, the inlet port, and the valve produce the turbulent effect of fuel mixture (b) fuel is injected into an auxiliary chamber that is separated from the cylinder by an orifice or throat (c) only a part of air charge is contained in an auxiliary chamber in which the fuel starts to burn with insufficient air which due to explosion tendency mixes thoroughly into main cylinder charge (d) there are no valves (e) fuel is partly burnt by spark. 231. For low load operation, more suitable (economical) engine is (a) S.I. engine (b) C.I. engine (c) both are equally good (d) multicylinder engine (e) two stroke engine. 232. A two stroke crank compressed engine has following ports in the cylinder (a) suction port and exhaust port (b) transfer port only (c) suction port and transfer port (d) transfer port and exhaust port (e) suction port, exhaust port and transfer port. 233. For the same size and weight, a two stroke engine as compared to four stroke engine will generate power (a) about twice (b) about 0.5 times (c) nearly equal (d) about 1.7 times (e) about 5 times. 234. A two stroke engine is usually identified by (a) size of flywheel (b) weight of engine (c) type of lubrication system Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (d) absence of valves (e) location of fuel tank. 235. If diesel is fed by mistake in the oil tank of a petrol engien, then engine will (a) give lot of smoke (b) detonate (c) knock (d) not run (e) run for some time and then stop. 236. The thermal efficiency of a semi-diesel cycle having fixed compression ratio and fixed quantity of heat, with increase in pressure ratio will (a) increase (b) decrease (c) remain unaffected (d) increase/decrease depending upon engine capacity (e) first increase and then decrease. 245. The termal efficiency of a petrol engine at design load is around (a) 90% (b) 50% (c) 40% (d) 30% (e) 15%. 246. In isochronous governing, speed droop is (a) 100% (b) 50% (c) 5% (c) 30% (e) 1%. 247. Method of governing used in petrol engine is (a) quantity governing (b) quality governing (c) combined governing (d) partial governing (e) hit and miss governing. 248. Pick up false statement (a) For petrol and large gas engines, quantity governingds preferred (b) In quantity governing, air fuel ratio is almost constant and quantity of charge is changed depending on load (c) In hit and miss governing, fuel supply is completely cut off during one or more number of cycles (d) In quality governing, quantity of fuel is varied to suit the load and total charge of air is varied (e) For close regulation of speed, combination of both quality and quantity governing is used. Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR 249. Method of governing used in diesel engine is (a) quantity governing (b) quality governing (c) combined governing (d) partial governing (e) nit and miss governing. 250. An engine has a normal speed of 960 r.p.m. and no load speed of 1000 r.p.m. The speed droop of governor will be about (a) 2% (b) 4% (c) 8% (d)±4% (e) 1%. 88 TOP Nuclear Power Plants - Mechanical Engineering Multiple Choice Questions and Answers List Latest Nuclear Power Plants Questions and Answers pdf free download 1. The efficiency of a nuclear power plant in comparsion to a conventional thermal power plant is (a) same (b) more (c) less (d) may be less or mote depending on size (e) unpredictable. Ans: c 2. Isotopes of same elements have (a) same atomic number and different masses (b) same chemical properties but different atomic numbers (c) different masses and different atomic numbers (d) different chemical properties and same atomic numbers (e) same chemical properties and same atomic numbers. Ans: b 3. Atomic number of an element in the periodic table represents the numbers of (a) protons in the nucleus (b) electrons in me nucleus (c) neutrons in the nucleus (d) electrons in the atom (e) neutrons in the atom. Ans: a 4. The mass number of a substance represents the sum of total number of Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (a) protons and neutrons in an atom (b) protons and electrons in an atom (c) neutrons and electrons in an atom (d) protons and neutrons in a nucleus (e) protons and electrons in a nucleus. Ans: d 5. Which is not identical for an atom and an isotope (a) mass number (b) atomic number (c) chemical properties (d) position in periodic table (e) all of the above. Ans: a 6. Amongst the following, the fissionable materials are (a) U233andPu239 (b) U23iandPu233 (c) U235andPu235 (d) U238andPu239 (e) U243andPu235 Ans: a 6. A nuclear unit becoming critical means (a) it is generating power to rated capacity (b) it is capable of generating much more than rated capacity (c) there is danger of nuclear spread (d) chain reaction that causes automatic splitting of the fuel nuclei has been established (e) it generates no heat. Ans: d 7. Moderator in nuclear plants is used to (a) reduce temperature (b) extract heat from nuclear reaction (c) control the reaction (d) cause collision with the fast moving neutrons to reduce their speed (e) moderate the radioactive pollution. Ans: d 8. The most commonly used moderator in nuclear plants is (a) heavy water (b) concrete and bricks (c) graphite and concrete (d) deutrium (e) graphite. Ans: e 9. The nuclear energy is measured as (a) MeV Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (b) curie (c) farads (d) MW (e) kWhr. Ans: a 10. The total energy released in fission of U is (a) 5 MeV (b) 10 MeV (c) 199 MeV (d) 168 MeV (e) 11 MeV. Ans: c 11. Breeder reactor has a conversion ratio of (a) unity (b) more than unity (c) less than unity (d) zero (e) infinity. Ans: b 12. Boiling water reactor employs (a) boiler (b) direct cycle of coolant system (c) double circuit system of coolant cycle (d) multi pass system (e) single circuit system. Ans: b 13. Fast breeder reactor uses (a) boiler (b) direct cycle of coolant system (c) double circuit system of coolant cycle (d) multi pass system (e) single circuit system. Ans: c 14. One gram of uranium will produce energy equivalent to approximately (a) 1 tonne of high grade coal (b) 4.5 tonnes of high grade coal (c) 10 tonnes of high grade coal (d) 100 tonnes of high grade coal (e) 1000 tonnes of high grade coal. Ans: b 15. Which of the following nuclear reactor does not need a heat exchanger for generation of steam (a) gas cooled (b) liquid metal cooled Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (c) pressurised water (d) boiling water (e) none of the above. Ans: d 16. The number of isotopes of hydrogen are (a) 1 (b) 2 (c) U (c) 3 (e) 0 Ans: c 17. The commonly used material for shielding is (a) lead or concrete (b) lead and tin (c) graphite or cadmium (d) thick galvanised sheets (e) black carbon papers. Ans: a 18. The main interest of shielding in nuclear reactor is protection against (a) X-rays (b) infra-red rays (c) a, P, and y rays (d) neutrons and gamma rays (e) electrons. Ans: d 19. Reflector in nuclear plants is used to (a) return the neutrons back into the core (b) shield the radioactivity completely (c) check polllution (d) conserve energy (e) is not used. Ans: a 20. The energy required to be applied to a radioactive nucleus for the emission of a neutron is (a) 1 MeV (b) 2.4 MeV (c) 4.3 MeV (d) 7.8 MeV (e) 20 MeV. Ans: d 21. Which of the following are ferrite materials (a) U233andPu239 (b) U (c) U238andPu239 Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (d) U238andTh239 (e) none of the above Ans: b 22. Ferrite material is (a) the most fissionable material (b) the basic fuel for nuclear paints (c) basic raw material for nuclear plants (d) the material which absorbs neutrons and undergoes spontaneous changes leading to the formation of fissionable material (e) none of the above. Ans: d 23. Enriched uranium is one in which (a) %age of U235 has been artificially in-creased (b) %age of U has been artificially increased (c) %age of U234 has been artificially in-creased (d) extra energy is pumped from outside (e) all impurities have been removed. Ans: a 24. Which of the following particles is the lightest (a) nucleus (b) electron (c) proton (d) meson (e) neutron. Ans: b 25. Which of the following is the heaviest (a) neutron (b) proton (c) atom (d) electron (e) nucleus. Ans: c 26. In fast breeder reactors (a) any type of moderator can be used (b) graphite is used as the moderator (c) heavy water is used as the moderator (d) moderator may or may not be used (e) moderator is dispensed with. Ans: e 27. In nuclear fission each neutron that causes fission releases (a) no new neutron (b) at least one new neutron (c) one new neutron (d) more than one new neutrons Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (e) many-fold neutrons. Ans: d 28. The breeding gain in case of thermal breeder reactor as compared to fast breeder reactor is (a) same (b) lower (c) higher (d) unity (e) higher/lower depending on the size of reactor. Ans: b 29. Gas cooled reactor uses following materials as moderator, and coolant (a) graphite, C02 (b) graphite, air (c) heavy water, C02 (d) lead, H2 (e) concrete, N2. Ans: a 30. A nuclear fission produces energy of following order in MeV (a) 20 (b) 200 (c) 2000 (d) 20,000 (e) 2 x 105. Ans: b 31. The process by which a heavy nucleus is splitted into two light nuclei is known as (a) splitting (b) fission (c) fusion (d) disintegration (e) chain reaction. Ans: b 32. A nuclear fission is initiated when the critical energy as compared to neutron binding energy of the atoms is (a) same (b) more (c) less (d) there is no such criterion (e) none of the above. Ans: b 33. The fast breeder reactor uses the following moderator (a) demineralised water (b) carbon dioxide (c) heavy water (d) graphite Like our facebook Page: https://www.facebook.com/NationalTestingServiceOfficialpage/?ref=bookmarks Join our group: https://www.facebook.com/groups/helpscholarships/?ref=bookmarks Prepared by BILAL NASIR (e) no moderator is used. Ans: e 34. The first unclear power plant in India is located at (a) Kota (b) Kalapakkam (c) Tarapur (d) Baraeilly (e) Kerala. Ans: c 35. The nuclear power plant at Tarapur has the following reactor (a) fast breeder (b) pressurised water (c) boiling water (d) sodium graphite (e) none of the above. Ans: c 35. Boiling water reactor uses the following as moderator, coolant and working fluid (a) ordinary fluid (b) heavy water (c) molten lead (d) hydrogen gas (e) none of the above. Ans: a 36. Ideally the neutron flux in reactor should be (a) maximum in center and zero at side (b) maximum at side and zero in center (c) uniform throughout (d) zero throughout (e) none of the above. Ans: c 37. Enriched uranium may contain fissionable contents of the order of (a) 1-99% (b) 1-25% (c) 1-50% (d) 1-75% (e) 1-90%. Ans: a 38. U235 will undergo fission by (a) high energy (fast) neutrons alone (b) low energy (slow) neutrons alone (c) either fast or slow neutrons (d) medium energy neutrons (e) none of the above