MCQOPTIONS
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MCQOPTIONS
This section includes 219 Mcqs, each offering curated multiple-choice questions to sharpen your Automobile Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
The absolute pressure of air at the outlet of a compressor is called |
| A. | back pressure |
| B. | critical pressure |
| C. | discharge pressure |
| D. | none of these |
| Answer» D. none of these | |
| 102. |
A receiver in compressor installations is used to damp pressure waves in compressor discharge. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 103. |
In jet propulsion power unit, the inlet duct of diverging shape is used for converting kinetic energy of air into pressure energy. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 104. |
In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during |
| A. | isothermal compression |
| B. | isentropic compression |
| C. | polytropic compression |
| D. | none of these |
| Answer» B. isentropic compression | |
| 105. |
The clearance, in a single stage, single acting reciprocating air compressor does not effect the workdone on the air and the power required for compressing the air. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 106. |
The multi-stage compression ofair as compared to single stage compression |
| A. | improves volumetric efficiency for the given pressure ratio |
| B. | reduces workdone per kg of air |
| C. | gives more uniform torque |
| D. | all of these |
| Answer» E. | |
| 107. |
In a turbo jet engine, subsequent to heat addition to compressed air, to get the power output, the working substance is expanded in |
| A. | exit nozzle, which is a constant volume process |
| B. | exit nozzle, which is essentially an isentropic process |
| C. | turbine blades, which is a constant volume process |
| D. | turbine blades, which is essentially an isentropic process |
| Answer» E. | |
| 108. |
The air is delivered __________ in one revolution in case of a three-lobbed rotor. |
| A. | two times |
| B. | three times |
| C. | four times |
| D. | six times |
| Answer» E. | |
| 109. |
The performance of air compressor at high altitudes will be __________ as compared to that at sea level. |
| A. | same |
| B. | lower |
| C. | higher |
| D. | None of these |
| Answer» C. higher | |
| 110. |
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. | reduced |
| B. | increased |
| C. | Can't say |
| D. | None of these |
| Answer» B. increased | |
| 111. |
A compressor must be driven by some prime mover. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 112. |
The ratio of the isentropic work to the Euler's work is known as pressure coefficient. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 113. |
In a gas turbine, air is obtained from the atmosphere and compressed in an air compressor. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 114. |
A rotary compressor is driven by an |
| A. | electric motor |
| B. | engine |
| C. | either (a) or (b) |
| D. | none of these |
| Answer» D. none of these | |
| 115. |
Rotary compressors are used for delivering |
| A. | small quantities of air at high pressures |
| B. | large quantities of air at high pressures |
| C. | small quantities of air at low pressures |
| D. | large quantities of air at low pressures |
| Answer» E. | |
| 116. |
Which of the following statement is correct relating to rocket engines ? |
| A. | The combustion chamber in a rocket engine is directly analogous to the reservoir of a super sonic wind tunnel |
| B. | The stagnation conditions exist at the combustion chamber |
| C. | The exit velocities of exhaust gases are much higher than those in jet engine |
| D. | all of the above |
| Answer» E. | |
| 117. |
The compressor capacity will be __________ if the temperature of intake air is lowest. |
| A. | lowest |
| B. | highest |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 118. |
The ratio of the discharge pressure to the inlet pressure of air is called |
| A. | compression ratio |
| B. | expansion ratio |
| C. | compressor efficiency |
| D. | volumetric efficiency |
| Answer» B. expansion ratio | |
| 119. |
A closed cycle gas turbine consists of a |
| A. | compressor |
| B. | heating chamber |
| C. | cooling chamber |
| D. | all of these |
| Answer» E. | |
| 120. |
The volume of air sucked by the compressor during its suction stroke is called |
| A. | free air delivery |
| B. | compressor capacity |
| C. | swept volume |
| D. | none of these |
| Answer» D. none of these | |
| 121. |
The intercooler pressure, for minimum work required, for a two stage reciprocating air compressor, is given by (where p1 = Intake pressure of air, p2 = Intercooler pressure, and p3 = Delivery pressure of air) |
| A. | p2 = p1 x p3 |
| B. | p2 = p1/p3 |
| C. | p2 = p1 x p3 |
| D. | p2 = p3/p1 |
| Answer» E. | |
| 122. |
Maximum work is saved in a two stage reciprocating air compressor with incomplete intercooling. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 123. |
The overall efficiency of the compressed air system is the |
| A. | ratio of shaft output of the air motor to the shaft input to the compressor |
| B. | ratio of shaft input to the compressor to the shaft output of air motor |
| C. | product of shaft output of air motor and shaft input to the compressor |
| D. | none of the above |
| Answer» B. ratio of shaft input to the compressor to the shaft output of air motor | |
| 124. |
For minimum work required to compress and deliver a quantity of air by multi-stage compression, |
| A. | the compression ratio in each stage should be same |
| B. | the intercooling should be perfect |
| C. | the workdone in each stage should be same |
| D. | all of the above |
| Answer» E. | |
| 125. |
The operation of the reciprocating air motor is similar to reciprocating air compressor. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 126. |
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 intercooler 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. | D1/D2 = p1p2 |
| B. | D1/D2 = p1/p2 |
| C. | D1/D2 = p2/p1 |
| D. | none of these |
| Answer» D. none of these | |
| 127. |
The compressor efficiency is defined as the ratio of volume of free air delivery per stroke to the swept volume of the piston. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 128. |
The operation of lifts, rams and pumps make use of compressed air. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 129. |
In a high pressure compressor, the delivery pressure is |
| A. | 1 to 5 bar |
| B. | 5 to 8 bar |
| C. | 8 to 10 bar |
| D. | 10 to 15 bar |
| Answer» D. 10 to 15 bar | |
| 130. |
The volumetric efficiency of a compressor |
| A. | increases with decrease in compression ratio |
| B. | decreases with decrease in compression ratio |
| C. | increases with increase in compression ratio |
| D. | decreases with increase in compression ratio |
| Answer» E. | |
| 131. |
The basic principle of the rocket propulsion is the same as that of jet propulsion. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 132. |
In a compressed air system, the temperature of air discharged from the air motor is __________ than the initial compressor intake temperature. |
| A. | more |
| B. | less |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 133. |
In an axial flow compressor, the ratio of pressure in theTOtor blades to the pressure rise in the compressor in one stage is known as |
| A. | work factor |
| B. | slip factor |
| C. | degree of reaction |
| D. | pressure coefficient |
| Answer» D. pressure coefficient | |
| 134. |
Which of the following bladings will give maximum pressure rise in a centrifugal compressor, assuming the same overall dimensions, blade inlet angle and rotational speeds ? |
| A. | Forward curved blades |
| B. | Backward curved blades |
| C. | Radial blades |
| D. | all of these |
| Answer» B. Backward curved blades | |
| 135. |
In a jet engine, the air-fuel ratio is |
| A. | 30:1 |
| B. | 40:1 |
| C. | 50:1 |
| D. | 60:1 |
| Answer» E. | |
| 136. |
Which one of the following is the effect of blade shape on performance of a centrifugal compressor ? |
| A. | Backward curved blades has poor efficiency |
| B. | Backward curved blades lead to stable performance |
| C. | Forward curved blades has higher efficiency |
| D. | Forward curved blades produce lower pressure ratio |
| Answer» E. | |
| 137. |
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. | p2 = (p1 + p3)/2 |
| B. | p2 = p1.p3 |
| C. | P2 = Pa x p3/p1 |
| D. | p2 = pa p3/p1 |
| Answer» C. P2 = Pa x p3/p1 | |
| 138. |
The axial flow compressor is preferred in air-craft gas turbines because of |
| A. | low frontal area |
| B. | higher thrust |
| C. | high pressure rise |
| D. | none of these |
| Answer» B. higher thrust | |
| 139. |
Free air is the air at atmospheric conditions at any specific location. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 140. |
The air power of the compressor is also known as |
| A. | indicated power |
| B. | brake power |
| C. | frictional power |
| D. | none of these |
| Answer» B. brake power | |
| 141. |
In a jet propulsion unit, the products of combustion after passing through the gas turbine are discharged into |
| A. | atmosphere |
| B. | vacuum |
| C. | discharge nozzle |
| D. | back to the compressor |
| Answer» D. back to the compressor | |
| 142. |
Only rocket engines can be propelled to space because |
| A. | they can generate very high thrust |
| B. | they have high propulsion efficiency |
| C. | these engines can work on several fuels |
| D. | they are not air-breathing engines |
| Answer» E. | |
| 143. |
A machine used to raise the pressure of air is called |
| A. | gas turbine |
| B. | I.C engine |
| C. | compressor |
| D. | air motor |
| Answer» D. air motor | |
| 144. |
In a compressor, work is done on the piston during suction of air and work is done by the piston during compression as well as delivery of air. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 145. |
The ratio of the isothermal power to the shaft power or brake power of the motor or engine required to drive the compressor is called overall isothermal efficiency. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 146. |
In a centrifugal compressor, the highest Mach number leading to shock wave in the fluid flow occurs at |
| A. | diffuser inlet radius |
| B. | diffuser outlet radius |
| C. | impeller inlet radius |
| D. | impeller outlet radius |
| Answer» C. impeller inlet radius | |
| 147. |
The degree of reaction is usually kept __________ for all types of axial flow compressors. |
| A. | 0.2 |
| B. | 0.3 |
| C. | 0.4 |
| D. | 0.5 |
| Answer» E. | |
| 148. |
The mean effective pressure of the compressor is the |
| A. | actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions |
| B. | volume of air delivered by the compressor |
| C. | volume of air sucked by the compressor during its suction stroke |
| D. | none of the above |
| Answer» E. | |
| 149. |
Gas turbine as compared to internal combustion engine |
| A. | can be driven at a very high speed |
| B. | produces uniform torque |
| C. | has more efficiency |
| D. | all of these |
| Answer» E. | |
| 150. |
The mass of gas turbine per kW developed is about __________ as that of an I.C. engine. |
| A. | same |
| B. | one-half |
| C. | one-fourth |
| D. | one-sixth |
| Answer» E. | |