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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.
| 101. |
For maximum work, the reheating should be done to an intermediate pressure of(Where p₁ = Maximum pressure, and p₂ = Minimum pressure) |
| A. | p₁ - p₂)/2 |
| B. | p₁ + p₂)/2 |
| C. | ₁/p₂ |
| D. | ₁ p₂ |
| Answer» E. | |
| 102. |
The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called |
| A. | lip factor |
| B. | elocity factor |
| C. | elocity coefficient |
| D. | one of the above |
| Answer» B. elocity factor | |
| 103. |
Which is false statement about advantages of multistage compressor in comparison to single stage compressor? |
| A. | ess power requirement |
| B. | etter mechanical balance |
| C. | ess loss of air due to leakage past the cylinder |
| D. | ower volumetric efficiency |
| Answer» E. | |
| 104. |
For minimum work required to compress and deliver a quantity of air by multistage compression |
| A. | he compression ratio in each stage should be same |
| B. | he intercooling should be perfect |
| C. | he work-done in each stage should be same |
| D. | ll of the above |
| Answer» E. | |
| 105. |
More than one stage will be preferred for reciprocating compressor if the delivery pressure is more than |
| A. | kg/cm² |
| B. | kg/cm² |
| C. | 0 kg/cm² |
| D. | 4.7 kg/cm² |
| Answer» B. kg/cm² | |
| 106. |
A rocket engine for the combustion of its fuel |
| A. | arries its own oxygen |
| B. | ses surrounding air |
| C. | ses compressed atmospheric air |
| D. | oes not require oxygen |
| Answer» B. ses surrounding air | |
| 107. |
If the flow of air through the compressor is parallel to its axis, then the compressor is |
| A. | eciprocating compressor |
| B. | entrifugal compressor |
| C. | xial flow compressor |
| D. | urbo compressor |
| Answer» D. urbo compressor | |
| 108. |
The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is |
| A. | eated |
| B. | ompressed air before entering the combustion chamber is heated |
| C. | led gas from turbine is heated and readmitted for complete expansion |
| D. | xhaust gases drive the compressor |
| Answer» C. led gas from turbine is heated and readmitted for complete expansion | |
| 109. |
Which is false statement about multistage compression? |
| A. | ower consumption per unit of air delivered is low |
| B. | olumetric efficiency is high |
| C. | t is best suited for compression ratios around 7:1 |
| D. | he moisture in air is condensed in the inter-cooler |
| Answer» C. t is best suited for compression ratios around 7:1 | |
| 110. |
The maximum combustion pressure in gas turbine as compared to I.C. engine is |
| A. | ore |
| B. | ess |
| C. | ame |
| D. | epends on other factors |
| Answer» C. ame | |
| 111. |
Mechanical efficiency of gas turbines as compared to I.C engines is |
| A. | igher |
| B. | ower |
| C. | ame |
| D. | one of the above |
| Answer» B. ower | |
| 112. |
Separators in compressor installations are located |
| A. | efore inter-cooler |
| B. | fter inter-cooler |
| C. | fter receiver |
| D. | etween after-cooler and air receiver |
| Answer» E. | |
| 113. |
A rocket engine uses __________ for the combustion of its fuel. |
| A. | urrounding air |
| B. | ompressed atmospheric air |
| C. | ts own oxygen |
| D. | one of these |
| Answer» D. one of these | |
| 114. |
To avoid moisture troubles, the branch connections from compressed air lines should be taken from |
| A. | op side of main |
| B. | ottom side of main |
| C. | eft side of main |
| D. | ight side of main |
| Answer» B. ottom side of main | |
| 115. |
Which of the following statement is correct as regard to centrifugal compressors? |
| A. | he flow of air is parallel to the axis of the compressor |
| B. | he static pressure of air in the impeller increases in order to provide centripetal force on the air |
| C. | he impeller rotates at high speeds |
| D. | he maximum efficiency is higher than multistage axial flow compressors |
| Answer» C. he impeller rotates at high speeds | |
| 116. |
Standard air is the air at ________ and relative humidity of 36 percent. |
| A. | .1 bar and 20°C |
| B. | bar and 20°C |
| C. | .1 bar and 40°C |
| D. | bar and 40°C |
| Answer» C. .1 bar and 40°C | |
| 117. |
Ram compression in turbojet involves |
| A. | eduction of speed of incoming air and conversion of part of it into pressure energy |
| B. | ompression of inlet air |
| C. | ncreasing speed of incoming air |
| D. | ost work |
| Answer» B. ompression of inlet air | |
| 118. |
Cylinder clearance in a compressor should be |
| A. | s large as possible |
| B. | s small as possible |
| C. | bout 50% of swept volume |
| D. | bout 100% of swept volume |
| Answer» C. bout 50% of swept volume | |
| 119. |
Axial flow compressor resembles |
| A. | entrifugal pump |
| B. | eciprocating pump |
| C. | urbine |
| D. | liding vane compressor |
| Answer» D. liding vane compressor | |
| 120. |
The blades of gas turbine are made of |
| A. | igh nickel alloy |
| B. | tainless steel |
| C. | arbon steel |
| D. | igh alloy steel |
| Answer» B. tainless steel | |
| 121. |
Ramjet engine |
| A. | s self operating at zero flight speed |
| B. | s not self operating at zero flight speed |
| C. | equires no air for its operation |
| D. | roduces a jet consisting of plasma |
| Answer» C. equires no air for its operation | |
| 122. |
The air is delivered ________ in one revolution in case of a three lobbed rotor. |
| A. | wo times |
| B. | hree times |
| C. | our times |
| D. | ix times |
| Answer» E. | |
| 123. |
If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix ‘I’ and ‘o’ stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity |
| A. | i = Vo |
| B. | t>Vo |
| C. | < Vo |
| D. | = Uo |
| Answer» B. t>Vo | |
| 124. |
For a two stage reciprocating compressor, compression from p₁ to p₃ is with perfect intercooling and no pressure losses. If compression in both the cylinders follows the same polytropic process and the atmospheric pressure is pa, then the intermediate pressure p₂ is given by |
| A. | ₂ = (p₁ + p₃)/2 |
| B. | ₂ = p₁. p₃ |
| C. | ₂ = Pa × p₃/p₁ |
| D. | ₂ = Pa p₃/p₁ |
| Answer» C. ₂ = Pa × p₃/p₁ | |
| 125. |
Diffuser in a compressor is used to |
| A. | ncrease velocity |
| B. | ake the flow streamline |
| C. | onvert pressure energy into kinetic energy |
| D. | onvert kinetic energy into pressure energy |
| Answer» E. | |
| 126. |
In a four stage compressor, if the pressure at the first and third stage is 1 bar and 16 bar, then the delivery pressure at the fourth stage will be |
| A. | bar |
| B. | 6 bar |
| C. | 4 bar |
| D. | 56 bar |
| Answer» D. 56 bar | |
| 127. |
Volumetric efficiency of air compressors is of the order of |
| A. | 0 - 30% |
| B. | 0 - 50% |
| C. | 0 - 70% |
| D. | 0 - 90% |
| Answer» E. | |
| 128. |
The compression ratio in a gas turbine is of the order of |
| A. | .5 : 1 |
| B. | : 1 |
| C. | : 1 |
| D. | 2 : 1 |
| Answer» D. 2 : 1 | |
| 129. |
The maximum compression ratio in an actual single stage axial flow compressor is of the order of |
| A. | : 1.2 |
| B. | : 2 |
| C. | : 5 |
| D. | : 10 |
| Answer» B. : 2 | |
| 130. |
Maximum temperature in a gas turbine is of the order of |
| A. | 00°C |
| B. | 000°C |
| C. | 500°C |
| D. | 000°C |
| Answer» B. 000°C | |
| 131. |
A 3 m³/min compressor means that it |
| A. | ompresses 3 m³/min of standard air |
| B. | ompresses 3 m³/ min of free air |
| C. | elivers 3 m³/ min of compressed air |
| D. | elivers 3 m³/ min of compressed air at delivery pressure |
| Answer» C. elivers 3 m³/ min of compressed air | |
| 132. |
Separators are generally used in air compressor installations |
| A. | efore the inter-cooler |
| B. | fter the inter-cooler |
| C. | etween the after-cooler and receiver |
| D. | efore first stage suction |
| Answer» D. efore first stage suction | |
| 133. |
Reheating in multistage expansion gas turbine results in |
| A. | igh thermal efficiency |
| B. | eduction in compressor work |
| C. | ecrease of heat loss in exhaust |
| D. | aximum work output |
| Answer» E. | |
| 134. |
Inter-cooling in gas turbine results in |
| A. | ncrease in net output but decrease in thermal efficiency |
| B. | ncrease in thermal efficiency but decrease in net output |
| C. | ncrease in both thermal efficiency and net output |
| D. | ecrease in both thermal efficiency and net output |
| Answer» B. ncrease in thermal efficiency but decrease in net output | |
| 135. |
A closed cycle gas turbine gives ________ efficiency as compared to an open cycle gas turbine. |
| A. | ame |
| B. | ower |
| C. | igher |
| D. | one of these |
| Answer» D. one of these | |
| 136. |
The ratio of specific weight/h.p. of gas turbine and I.C engines may be typically of the order of |
| A. | : 1 |
| B. | : 1 |
| C. | : 1 |
| D. | : 6 |
| Answer» E. | |
| 137. |
The volumetric efficiency of a compressor |
| A. | ncreases with decrease in compression ratio |
| B. | ecreases with decrease in compression ratio |
| C. | ncreases with increase in compression ratio |
| D. | ecreases with increase in compression ratio |
| Answer» E. | |
| 138. |
A rocket works with maximum overall efficiency when air craft velocity is equal to the |
| A. | et velocity |
| B. | wice the jet velocity |
| C. | alf the jet velocity |
| D. | verage of the jet velocity |
| Answer» D. verage of the jet velocity | |
| 139. |
When air is to be compressed at a high pressure, then it is advantageous to use |
| A. | ingle stage compression |
| B. | ultistage compression without intercooling |
| C. | ultistage compression with intercooling |
| D. | one of these |
| Answer» D. one of these | |
| 140. |
For speed above 3000 km/hour, it is more advantageous to use |
| A. | urbojet engine |
| B. | amjet engine |
| C. | ropellers |
| D. | ockets |
| Answer» C. ropellers | |
| 141. |
Which is false statement about air receivers? |
| A. | hese are used to dampen pulsations |
| B. | hese act as reservoir to take care of sudden demands |
| C. | hese increase compressor efficiency |
| D. | hese knock out some oil and moisture |
| Answer» D. hese knock out some oil and moisture | |
| 142. |
Aeroplanes employ following type of compressor~! |
| A. | Radial flow |
| B. | Axial flow |
| C. | Centrifugal |
| D. | None of the above |
| Answer» C. Centrifugal | |
| 143. |
The volume of air delivered by the compressor is called%! |
| A. | Free air delivery |
| B. | Compressor capacity |
| C. | Swept volume |
| D. | None of these |
| Answer» C. Swept volume | |
| 144. |
Reheating in multistage expansion gas turbine results in%! |
| A. | High thermal efficiency |
| B. | Reduction in compressor work |
| C. | Decrease of heat loss in exhaust |
| D. | Maximum work output |
| Answer» E. | |
| 145. |
Water gas is produced by%! |
| A. | Carbonisation of coal |
| B. | Passing steam over incandescent coke |
| C. | Passing air and a large amount of steam over waste coal at about 65°C |
| D. | Partial combustion of coal, eke, anthracite coal or charcoal in a mixed air steam blast |
| Answer» C. Passing air and a large amount of steam over waste coal at about 65¬¨‚àûC | |
| 146. |
1 m of air at atmospheric condition weighs approximately%! |
| A. | 0.5 kg |
| B. | 1.0 kg |
| C. | 1.3 kg |
| D. | 2.2 kg |
| Answer» D. 2.2 kg | |
| 147. |
A closed cycle gas turbine works on%! |
| A. | Carnot cycle |
| B. | Rankine cycle |
| C. | Ericsson cycle |
| D. | Joule cycle |
| Answer» E. | |
| 148. |
Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm. The air pressure will be%! |
| A. | 1.03 kg/cm² |
| B. | 1.06 kg/cm² |
| C. | 1.00 kg/cm² |
| D. | 0.53 kg/cm² |
| Answer» D. 0.53 kg/cm¬¨‚⧠| |
| 149. |
A centrifugal compressor works on the principle of%! |
| A. | Conversion of pressure energy into kinetic energy |
| B. | Conversion of kinetic energy into pressure energy |
| C. | Centripetal action |
| D. | Generating pressure directly |
| Answer» C. Centripetal action | |
| 150. |
The output of a gas turbine is 300 KW and its efficiency is 20 percent, the heat supplied is%! |
| A. | 6000 KW |
| B. | 15 KW |
| C. | 600 KW |
| D. | 150 KW |
| Answer» C. 600 KW | |