MCQOPTIONS
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MCQOPTIONS
This section includes 454 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. |
Gas turbine as compared to internal combustion engine |
| A. | an be driven at a very high speed |
| B. | roduces uniform torque |
| C. | as more efficiency |
| D. | ll of these |
| Answer» E. | |
| 52. |
In a turbo jet engine, subsequent to heat addition to compressed air, to get the power output, the working substance is expanded in |
| A. | xit nozzle, which is a constant volume process |
| B. | xit nozzle, which is essentially an isentropic process |
| C. | urbine blades, which is a constant volume process |
| D. | urbine blades, which is essentially an isentropic process |
| Answer» E. | |
| 53. |
The gas in cooling chamber of a closed cycle gas turbine is cooled at |
| A. | onstant volume |
| B. | onstant temperature |
| C. | onstant pressure |
| D. | one of these |
| Answer» D. one of these | |
| 54. |
The maximum propulsion efficiency of a turbojet is attained at around following speed |
| A. | 50 km/hr |
| B. | 050 km/hr |
| C. | 700 km/hr |
| D. | 400 km/hr |
| Answer» E. | |
| 55. |
The overall isothermal efficiency of compressor is defined as the ratio of |
| A. | sothermal h.p. to the BHP of motor |
| B. | sothermal h.p. to adiabatic h.p. |
| C. | ower to drive compressor to isothermal h.p. |
| D. | ork to compress air isothermally to work for actual compression |
| Answer» B. sothermal h.p. to adiabatic h.p. | |
| 56. |
The velocity of air entering in a rocket is _________ as compared to an aircraft. |
| A. | ero |
| B. | ess |
| C. | ore |
| D. | ame |
| Answer» B. ess | |
| 57. |
An air receiver is to be placed outside. Should it be placed in |
| A. | un |
| B. | hade |
| C. | ain |
| D. | nclosed room |
| Answer» C. ain | |
| 58. |
In jet engines the products of combustion after passing through the gas turbine are discharged into |
| A. | tmosphere |
| B. | ack to the compressor |
| C. | ischarge nozzle |
| D. | acuum |
| Answer» D. acuum | |
| 59. |
In a jet propulsion unit, the products of combustion after passing through the gas turbine are discharged into |
| A. | tmosphere |
| B. | acuum |
| C. | ischarge nozzle |
| D. | ack to the compressor |
| Answer» D. ack to the compressor | |
| 60. |
A compressor at high altitudes will require ________ power. |
| A. | ame |
| B. | ess |
| C. | ore |
| D. | one of these |
| Answer» C. ore | |
| 61. |
The efficiency of the vane blower is (where W₁ = Workdone due to compression, and W₂ = Workdone due to back flow) |
| A. | ₁/(W₁ + W₂) |
| B. | ₂/(W₁ + W₂) |
| C. | W₁ + W₂)/W₁ |
| D. | W₁ + W₂)/W₂ |
| Answer» C. W₁ + W₂)/W₁ | |
| 62. |
The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. is |
| A. | ow |
| B. | igh |
| C. | ame |
| D. | ow/high depending on make and type |
| Answer» B. igh | |
| 63. |
The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation |
| A. | .1% |
| B. | .5% |
| C. | .0% |
| D. | % |
| Answer» D. % | |
| 64. |
1 m of air at atmospheric condition weighs approximately |
| A. | .5 kg |
| B. | .0 kg |
| C. | .3 kg |
| D. | .2 kg |
| Answer» D. .2 kg | |
| 65. |
The efficiency of roots blower ________ with the increase in pressure ratio. |
| A. | ecreases |
| B. | ncreases |
| C. | oes not change |
| D. | one of these |
| Answer» B. ncreases | |
| 66. |
For a two stage compressor, if index of compression for higher stage is greater than index of compression for lower stage, then the optimum pressure as compared to ideal case will |
| A. | ncrease |
| B. | ecrease |
| C. | emain unaffected |
| D. | ther factors control it |
| Answer» B. ecrease | |
| 67. |
The process, which causes the air to enter the impeller blades of a centrifugal compressor at ________ velocity (without effecting the mass of air to flow and velocity of flow) is known as prewhirl. |
| A. | educed |
| B. | ncreased |
| C. | ero |
| D. | one of these |
| Answer» B. ncreased | |
| 68. |
The power available for takeoff and climb in case of turbojet engine as compared to reciprocating engine is |
| A. | ess |
| B. | ore |
| C. | ame |
| D. | ay be less or more depending on ambient conditions |
| Answer» B. ore | |
| 69. |
Which of the following statement is correct relating to rocket engines? |
| A. | he combustion chamber in a rocket engine is directly analogous to the reservoir of a supersonic wind tunnel |
| B. | he stagnation conditions exist at the combustion chamber |
| C. | he exit velocities of exhaust gases are much higher than those in jet engine |
| D. | ll of the above |
| Answer» E. | |
| 70. |
Volumetric efficiency of a compressor decreases with ________ in compression ratio. |
| A. | ecrease |
| B. | ncrease |
| C. | emain same |
| D. | oes not change |
| Answer» C. emain same | |
| 71. |
If p₁ is the pressure of air entering the L.P, cylinder and p₃ is the pressure of air leaving the H.P. cylinder, then the ratio of cylinder diameters for a single acting, two stage reciprocating compressor with complete intercooling is given by |
| A. | ₁/D₂ = (p₁ p₃)1/2 |
| B. | ₁/D₂ = (p₁/p₃)1/4 |
| C. | ₁/D₂ = (p₁ p₃)1/4 |
| D. | ₁/D₂ = (p₃/p₁)1/4 |
| Answer» E. | |
| 72. |
In n₁ and n₂ are the indices of compression for the first and second stage of compression, then the ratio of work-done on the first and second stages (W₁/W₂) with perfect intercooling is given by |
| A. | ₁/W₂ = n₂(n₁ - 1)/n₁(n₂ - 1) |
| B. | ₁/W₂ = n₁(n₂ - 1)/n₂(n₁ - 1) |
| C. | ₁/W₂ = n₁/n₂ |
| D. | ₁/W₂ = n₂/n₁ |
| Answer» C. ₁/W₂ = n₁/n₂ | |
| 73. |
If p₁, is the pressure of air entering the L.P. cylinder and p₂ is the pressure of air leaving the L.P. cylinder (or inter-cooler pressure), then the ratio of cylinder diameters for a single acting, two stage reciprocating air compressor with complete intercooling is given by (where D₁ = Dia. of L.P. cylinder, and D₂ = Dia. of H.P. cylinder) |
| A. | ₁/D₂ = p₁ p₂ |
| B. | ₁/D₂ = p₁/p₂ |
| C. | ₁/D₂ = p₂/p₁ |
| D. | one of these |
| Answer» D. one of these | |
| 74. |
Maximum work is done in compressing air when the compression is |
| A. | sothermal |
| B. | diabatic |
| C. | olytropic |
| D. | one of the above |
| Answer» C. olytropic | |
| 75. |
The performance of air compressor at high altitudes will be ________ as compared to that at sea level. |
| A. | ame |
| B. | ower |
| C. | igher |
| D. | one of these |
| Answer» C. igher | |
| 76. |
The thrust on the rotor in a centrifugal compressor is produced by |
| A. | adial component |
| B. | xial component |
| C. | angential component |
| D. | one of the above |
| Answer» C. angential component | |
| 77. |
For supplying intermittent small quantity of air at high pressure, following compressor is best suited |
| A. | entrifugal |
| B. | eciprocating |
| C. | xial |
| D. | crew |
| Answer» C. xial | |
| 78. |
Out of the following, from where you will prefer to take intake for air compressor |
| A. | rom an air conditioned room maintained at 20°C |
| B. | rom outside atmosphere at 1°C |
| C. | rom coal yard side |
| D. | rom a side where cooling tower is located nearby |
| Answer» E. | |
| 79. |
In a single stage, single acting reciprocating air compressor, without clearance, the work-done on the air during isentropic compression is ________ the heat required to raise the temperature of air from T₁ to T₂ at a constant pressure. |
| A. | qual to |
| B. | ess than |
| C. | reater than |
| D. | one of these |
| Answer» B. ess than | |
| 80. |
Axial flow compressor has the following advantage over centrifugal compressor |
| A. | arger air handling ability per unit frontal area |
| B. | igher pressure ratio per stage |
| C. | erofoil blades are used |
| D. | igher average velocities |
| Answer» B. igher pressure ratio per stage | |
| 81. |
If the clearance ratio for a reciprocating air compressor is 'K', then its volumetric efficiency is given by |
| A. | - k + k (p₁/p₂)1/n |
| B. | + k - k (p₂/p₁)1/n |
| C. | - k + k (p₁/p₂) n- 1/n |
| D. | + k - k (p₂/p₁) n-1/n |
| Answer» C. - k + k (p₁/p₂) n- 1/n | |
| 82. |
In a centrifugal compressor, the highest Mach number leading to shock wave in the fluid flow occurs at |
| A. | iffuser inlet radius |
| B. | iffuser outlet radius |
| C. | mpeller inlet radius |
| D. | mpeller outlet radius |
| Answer» C. mpeller inlet radius | |
| 83. |
The volumetric efficiency of a compressor falls roughly as follows for every 5°C increase in atmospheric temperature |
| A. | .1% |
| B. | .5% |
| C. | % |
| D. | % |
| Answer» D. % | |
| 84. |
During base load operation, the best method of controlling compressor is |
| A. | tart-stop motor |
| B. | onstant speed unloader |
| C. | elief valve |
| D. | ariable speed |
| Answer» B. onstant speed unloader | |
| 85. |
A closed cycle gas turbine consists of a |
| A. | ompressor |
| B. | eating chamber |
| C. | ooling chamber |
| D. | ll of these |
| Answer» E. | |
| 86. |
In a centrifugal compressor, the ratio of the ________ to the blade velocity is called slip factor. |
| A. | nlet whirl velocity |
| B. | utlet whirl velocity |
| C. | nlet velocity of flow |
| D. | utlet velocity of flow |
| Answer» E. | |
| 87. |
For slow speed large capacity compressor, following type of valve will be best suited |
| A. | oppet valve |
| B. | echanical valve of the Corliss, sleeve, rotary or semi rotary type |
| C. | isc or feather type |
| D. | ny of the above |
| Answer» D. ny of the above | |
| 88. |
It is not possible to use closed gas turbine cycle in aeronautical engines because |
| A. | t is inefficient |
| B. | t is bulky |
| C. | t requires cooling water for its operation |
| D. | one of the above |
| Answer» D. one of the above | |
| 89. |
Euler's equation is applicable for |
| A. | entrifugal compressor |
| B. | xial compressor |
| C. | umps |
| D. | ll of the above |
| Answer» E. | |
| 90. |
The propulsive power of the rocket is (where v₁ = Jet velocity, and v₂ = Aircraft velocity) |
| A. | v₁² -v₂²)/2g |
| B. | v₁ - v₂)²/2g |
| C. | v₁² -v₂²)/g |
| D. | v₁ - v₂)²/g |
| Answer» B. v₁ - v₂)²/2g | |
| 91. |
In a single acting reciprocating air compressor, without clearance, the compression of air may be |
| A. | sothermal |
| B. | olytropic |
| C. | sentropic |
| D. | ny one of these |
| Answer» E. | |
| 92. |
The most efficient method of compressing air is to compress it |
| A. | sothermally |
| B. | diabatically |
| C. | sentropically |
| D. | sochronically |
| Answer» B. diabatically | |
| 93. |
In a centrifugal compressor, the flow of air is ________ to the axis of compressor. |
| A. | arallel |
| B. | erpendicular |
| C. | nclined |
| D. | one of these |
| Answer» C. nclined | |
| 94. |
In a single stage, single acting reciprocating air compressor, without clearance volume, the work-done is minimum during |
| A. | sothermal compression |
| B. | sentropic compression |
| C. | olytropic compression |
| D. | one of these |
| Answer» B. sentropic compression | |
| 95. |
With the decrease in compression ratio, the volumetric efficiency |
| A. | oes not change |
| B. | ncreases |
| C. | ecreases |
| D. | irst decrease and then increase |
| Answer» C. ecreases | |
| 96. |
In which case the air-fuel ratio is likely to be maximum? |
| A. | as turbine |
| B. | -stroke petrol engine |
| C. | -stroke diesel engine |
| D. | ulti cylinder engine |
| Answer» B. -stroke petrol engine | |
| 97. |
An ideal air compressor cycle with clearance on P-V diagram can be represented by following processes |
| A. | ne adiabatic, two isobaric, and one constant volume |
| B. | wo adiabatic and two isobaric |
| C. | wo adiabatic, one isobaric and one constant volume |
| D. | ne adiabatic, one isobaric and two constant volumes |
| Answer» C. wo adiabatic, one isobaric and one constant volume | |
| 98. |
Euler's equation can be used for |
| A. | adial flow compressors |
| B. | xial flow compressors |
| C. | umps |
| D. | ll of these |
| Answer» E. | |
| 99. |
The thrust of a jet propulsion power unit can be increased by |
| A. | njecting water into the compressor |
| B. | urning fuel after gas turbine |
| C. | njecting ammonia into the combustion chamber |
| D. | ll of the above |
| Answer» E. | |
| 100. |
The efficiency and work ratio of a gas turbine plant can be increased by |
| A. | dding heat exchanger |
| B. | njecting water in/around combustion chamber |
| C. | eheating the air after partial expansion in the turbine |
| D. | ll of the above |
| Answer» E. | |