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MCQOPTIONS
This section includes 463 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Ratio of indicated h.p. to shaft h.p. is known as |
| A. | compressor efficiency |
| B. | isothermal efficiency |
| C. | volumetric efficiency |
| D. | mechanical efficiency |
| Answer» E. | |
| 52. |
Heat transfer takes place as per - |
| A. | zeroth law of thermodynamics |
| B. | first law of thermodynamic |
| C. | second law of the thermodynamics |
| D. | Kirchhoff law (e) Stefan's law. |
| Answer» D. Kirchhoff law (e) Stefan's law. | |
| 53. |
When a nozzle operates with maximum mass flow, it is said to be |
| A. | under expanding flow |
| B. | over expanding flow |
| C. | choked flow |
| D. | none of the above |
| Answer» D. none of the above | |
| 54. |
A condenser where circulating water flows through tubes which are surrounded by steam,is known as......... |
| A. | Surface condenser |
| B. | Jet condenser |
| C. | Barometric condenser |
| D. | Evaporative condenser |
| Answer» B. Jet condenser | |
| 55. |
The absolute pressure in a condenser is given by |
| A. | Pabs = Patm + Pvacuum |
| B. | Pabs = Patm -Pvacuum |
| C. | Pabs = Pvacuum |
| D. | none of the above |
| Answer» C. Pabs = Pvacuum | |
| 56. |
The state of vapour under saturation condition is described by |
| A. | pressure alone |
| B. | temperature alone |
| C. | pressure and temperature |
| D. | pressure and dryness fraction |
| Answer» E. | |
| 57. |
In a reaction turbine, steam expands |
| A. | in the nozzle only |
| B. | in the moving blades only |
| C. | in the fixed and moving blades |
| D. | none of the above |
| Answer» D. none of the above | |
| 58. |
If the temperature of a solid surface changes from 27°C to 627°C, then its emissive power changes in the ratio of |
| A. | 3 |
| B. | 81 |
| C. | 9 |
| D. | 27 |
| Answer» C. 9 | |
| 59. |
The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of aperfectly black body. This statement is known as |
| A. | Krichoff's law |
| B. | Stefan's law |
| C. | Wien' law |
| D. | Planck's law |
| Answer» B. Stefan's law | |
| 60. |
Air leakage into the condenser reduces |
| A. | turbine output |
| B. | cooling capacity |
| C. | life of condenser |
| D. | all of the above |
| Answer» E. | |
| 61. |
From inlet to exit of moving blades in case of impulse turbine, the pressure |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | none of the above |
| Answer» D. none of the above | |
| 62. |
The function of a condenser in a thermal power plant is....... |
| A. | To act as reservior to receive steam for turbine |
| B. | To condense steam into condensate to be reused again |
| C. | To create vaccum |
| D. | All of the above |
| Answer» E. | |
| 63. |
In a high-level jet condenser, the condenser shell is installed at a height of |
| A. | more than 5.5 m |
| B. | more than 10.33 m |
| C. | less than 10.33 m |
| D. | none of the above |
| Answer» C. less than 10.33 m | |
| 64. |
In evaporative condensers, the condensing of steam is achieved |
| A. | by rejecting heat to surrounding air |
| B. | by rejecting heat to coolant |
| C. | by evaporation of some coolant |
| D. | none of the above |
| Answer» D. none of the above | |
| 65. |
In a pressure-compounded impulse steam turbine, as compared to velocity compounding, the number of stages is |
| A. | less |
| B. | more |
| C. | same |
| D. | none of the above |
| Answer» C. same | |
| 66. |
For water, at pressures below atmospheric, |
| A. | melting point rises slightly and boiling point drops markedly |
| B. | melting point rises markedly and boiling point drops markedly |
| C. | melting point drops slightly and boiling point drops markedly |
| D. | melting point drops slightly and boiling point drops slightly |
| Answer» B. melting point rises markedly and boiling point drops markedly | |
| 67. |
In regenerative type heat exchanger, heat transfer takes place by |
| A. | direct mixing of hot and cold fluids |
| B. | a complete separation between hot and cold fluids |
| C. | flow of hot and cold fluids alternately over a surface |
| D. | indirect tr |
| Answer» B. a complete separation between hot and cold fluids | |
| 68. |
Frictional losses in the nozzle |
| A. | reduces the heat drop |
| B. | increases the heat drop |
| C. | has no effect on heat drop |
| D. | none of the above |
| Answer» B. increases the heat drop | |
| 69. |
For the flow through the convergent and divergent nozzle, whole of friction loss is assumed |
| A. | in the converging portion |
| B. | in the divergent portion |
| C. | between inlet and outlet |
| D. | none of the above |
| Answer» C. between inlet and outlet | |
| 70. |
The function of a condenser in a steam power plant is |
| A. | to reduce back pressure |
| B. | to condense the exhaust steam |
| C. | to reduce specific volume of fluid |
| D. | all of the above |
| Answer» E. | |
| 71. |
Heat conducted through unit area and unit thick face per unit time when temperature difference between opposite facesis unity,is called |
| A. | thermal resistance |
| B. | thermal coefficient |
| C. | temperature gradient |
| D. | thermal conductivity |
| Answer» E. | |
| 72. |
The vloumetric efficiency of compressor with increase in compression ratio will |
| A. | increase |
| B. | decrease |
| C. | remain same |
| D. | may increase/decrease depending on clearance volume |
| Answer» C. remain same | |
| 73. |
One kg of steam sample contains 0.8 kg dry steam; it's dryness fraction is |
| A. | 0.2 |
| B. | 0.8 |
| C. | 1.0 |
| D. | 0.6 |
| Answer» C. 1.0 | |
| 74. |
The actual vaccum in a condenser is equal to...... |
| A. | Barometric pressure + actual pressure |
| B. | Barometric pressure - actual pressure |
| C. | Gauge pressure + atmospheric pressure |
| D. | Gauge pressure - atmospheric pressure |
| Answer» C. Gauge pressure + atmospheric pressure | |
| 75. |
For supersaturated flow in the nozzle, the discharge |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | none of the above |
| Answer» B. decreases | |
| 76. |
The steam turbines is a |
| A. | rotary machine |
| B. | reciprocating machine |
| C. | rotodynamic machine |
| D. | none of the above |
| Answer» D. none of the above | |
| 77. |
In heat transfer, conductance equals conductivity (kcal/hr/sqm/°C/cm) divided by |
| A. | hr (time) |
| B. | sqm (area) |
| C. | °C (temperature) |
| D. | cm (thickness) |
| Answer» E. | |
| 78. |
Which of the following is a water tube boiler |
| A. | Lancashire boiler |
| B. | Cochran boiler |
| C. | Cornish boiler |
| D. | Babcock and Wilcox boiler |
| Answer» E. | |
| 79. |
According to Kirchoff's law, ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a |
| A. | grey body |
| B. | brilliant white polished body |
| C. | red hot body |
| D. | black body |
| Answer» E. | |
| 80. |
The ratio of heat utilised to produce steam and the heat liberated in furnace is known as |
| A. | boiler effectiveness |
| B. | boiler evaporative capacity |
| C. | factor of evaporation |
| D. | boiler efficiency. |
| Answer» E. | |
| 81. |
At ideal condition of vapour power cycle, reversible constant pressure heat rejection is carried out at |
| A. | boiler |
| B. | turbine |
| C. | condenser |
| D. | feed pump |
| Answer» D. feed pump | |
| 82. |
Ideal expansion of steam through a nozzle is considered |
| A. | isothermal |
| B. | adiabatic |
| C. | polytropic |
| D. | none of the above |
| Answer» C. polytropic | |
| 83. |
According to Dalton’s law, the total pressure 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 |
| Answer» D. sum of the partial pressures of all divided by average molecular weight | |
| 84. |
The lenght of Cornish boiler is of the order of |
| A. | 2-4 m |
| B. | 3-5 m |
| C. | 5-7.5 m |
| D. | 7-9 m |
| Answer» D. 7-9 m | |
| 85. |
Which ideal process is carried out at the turbine in vapour power cycle? |
| A. | reversible adiabatic compression |
| B. | reversible adiabatic expansion |
| C. | reversible constant pressure heat addition |
| D. | reversible constant pressure heat rejection |
| Answer» C. reversible constant pressure heat addition | |
| 86. |
The ratio of actual vaccum to the ideal vaccum in a condenser is called....... |
| A. | Condenser efficiency |
| B. | Vaccum efficiency |
| C. | Boiler efficiency |
| D. | Nozzle efficiency |
| Answer» C. Boiler efficiency | |
| 87. |
Dalton's law of partial pressure, applicable to condensers, states that |
| A. | Pa = Pabs + Psat |
| B. | Psat = Pabs + Pa |
| C. | Pabs = Pa+ Psat |
| D. | none of the above |
| Answer» D. none of the above | |
| 88. |
The dry saturated steam at very high pressure (150-200 kg/cm2) when throttled to atmosphere will become |
| A. | wet |
| B. | superheated |
| C. | remain dry saturated |
| D. | dry |
| Answer» B. superheated | |
| 89. |
The- most efficient method of compressing air is to compress it |
| A. | isothermally |
| B. | adiabatically |
| C. | isentropically |
| D. | isochronically |
| Answer» B. adiabatically | |
| 90. |
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 |
| Answer» C. 1.27 | |
| 91. |
Heat is transferred by all three modes of transfer (conduction, convection and radiation) in, |
| A. | electric heater |
| B. | steam condenser |
| C. | melting of ice |
| D. | boiler. |
| Answer» E. | |
| 92. |
How is water circulated throughout the dry cooling tower system? |
| A. | finned tubes |
| B. | metal pipes |
| C. | porous tubes |
| D. | swirling tubes |
| Answer» B. metal pipes | |
| 93. |
Select the disadvantage of cooling pond out of the given? |
| A. | the area required of cooling in a cooling pond is small |
| B. | spray losses due to evaporation and windage run high |
| C. | there is no control over the temperature of cooled water |
| D. | the cooling efficiency is low compared with cooling water |
| Answer» D. the cooling efficiency is low compared with cooling water | |
| 94. |
Water is used as a          in air conditioning units. |
| A. | absorbent |
| B. | refrigerant |
| C. | absorbent and refrigerant |
| D. | none of the mentioned |
| Answer» C. absorbent and refrigerant | |
| 95. |
The vapour going to condenser is          in temperature and          in ammonia. |
| A. | higher, less |
| B. | higher, richer |
| C. | lower, less |
| D. | lower, richer |
| Answer» E. | |
| 96. |
A condenser must          and then          the compressed refrigerant. |
| A. | superheat, evaporate |
| B. | desuperheat, evaporate |
| C. | superheat, condense |
| D. | desuperheat, condense |
| Answer» E. | |
| 97. |
Superheating of vapour and subcooling of liquid          the refrigerating effect. |
| A. | decreases |
| B. | increases |
| C. | no change |
| D. | none of the mentioned |
| Answer» C. no change | |
| 98. |
In vapour refrigeration cycle, which of the following is used for expansion? |
| A. | expansion engine |
| B. | throttling valve or capillary tube |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 99. |
In pressure compounded turbines flow passage is from |
| A. | moving nozzles to fixed blades |
| B. | fixed nozzles to moving blades |
| C. | fixed blades to moving nozzles |
| D. | none of the mentioned |
| Answer» C. fixed blades to moving nozzles | |
| 100. |
In pressure compounded turbines moving nozzles are followed by turbine blades. |
| A. | true |
| B. | false |
| Answer» C. | |