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MCQOPTIONS
This section includes 2670 Mcqs, each offering curated multiple-choice questions to sharpen your Railways knowledge and support exam preparation. Choose a topic below to get started.
| 401. |
The degree of reaction of a turbo machine is defined as the ratio of the: |
| A. | Static pressure change in the rotor to that in the stator |
| B. | Static pressure change in the rotor to that is the stage. |
| C. | Static pressure change in the stator to that is the rotor. |
| D. | Total pressure change in the rotor to that in the stage. |
| Answer» C. Static pressure change in the stator to that is the rotor. | |
| 402. |
A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed is: |
| A. | 5367 rpm |
| B. | 6000 rpm |
| C. | 9360 rpm |
| D. | 12000 rpm |
| Answer» B. 6000 rpm | |
| 403. |
A reverted gear train is one in which the output shaft |
| A. | Rotate in opposite directions |
| B. | Are co-axial |
| C. | Are at right angles to each other |
| D. | Are at an angle to each other |
| Answer» C. Are at right angles to each other | |
| 404. |
A rotor which is balanced statically but not dynamically is supported on two ball bearings L apart and at high speed of the rotor, reaction of the left bearing is R. The right side of the bearing is shifted to a new position 2L apart from the left bearing: At the same rotor speed, dynamic reaction on the left bearing in the new arrangement will: |
| A. | Remain same as before |
| B. | Become equal to 2R |
| C. | Become equal to \[\frac{1}{2}R\] |
| D. | Become equal to \[\frac{1}{4}R\] |
| Answer» B. Become equal to 2R | |
| 405. |
Which one of the following is the shock that occurs for an airplane travelling at supersonic speed? |
| A. | Normal shock |
| B. | Oblique shock |
| C. | Bow shock |
| D. | Air shock |
| Answer» B. Oblique shock | |
| 406. |
Nichrome wires can be safely used for heating to temperature around\[1500{}^\circ C\].Which of the following materials for heating elements should be selectd? |
| A. | Eureka |
| B. | Kanthal |
| C. | Platimum moly benum, carbon compound |
| D. | Nichrome |
| Answer» D. Nichrome | |
| 407. |
At a certain section at a distance 'x' from one of the supports of a simply supported beam, the intensity of loading, bending moment and shear force are \[{{\text{W}}_{x}},{{M}_{x}},\] and \[{{V}_{x}},\] respectively, if the intensity of loading is varying continuously along the length of the beam, them the invalid relation is: |
| A. | \[Slop,\,\,{{Q}_{x}}=\frac{Mx}{Vx}\] |
| B. | \[{{V}_{x}}=\frac{dMx}{dx}\] |
| C. | \[{{W}_{x}}=\frac{{{d}^{2}}Mx}{d{{x}^{2}}}\] |
| D. | \[{{W}_{x}}=\frac{d{{V}_{x}}}{dx}\] |
| Answer» B. \[{{V}_{x}}=\frac{dMx}{dx}\] | |
| 408. |
A reversible heat engine runs between high temperature \[{{T}_{1}}\] and low temperature \[{{T}_{2}}.\] the work output of this heat engine is used to run a reversible refrigeration cycle absorbing heat at temperature \[{{T}_{3}}\] and rejecting at temperature \[{{T}_{2}}.\]what is the COP of the combined system? |
| A. | \[\left( \frac{{{T}_{1}}-{{T}_{2}}}{{{T}_{1}}} \right)\,\,\left( \frac{{{T}_{3}}}{{{T}_{2}}-{{T}_{3}}} \right)\] |
| B. | \[\left( \frac{{{T}_{2}}}{{{T}_{1}}-{{T}_{2}}} \right)\,\,\left( \frac{{{T}_{2}}-{{T}_{3}}}{{{T}_{3}}} \right)\] |
| C. | \[\left( \frac{{{T}_{1}}}{{{T}_{1}}-{{T}_{2}}} \right)\,\,\left( \frac{{{T}_{3}}}{{{T}_{2}}-{{T}_{3}}} \right)\] |
| D. | \[\left( \frac{{{T}_{3}}}{{{T}_{1}}-{{T}_{3}}} \right)\,\,\left( \frac{{{T}_{1}}}{{{T}_{2}}-{{T}_{1}}} \right)\] |
| Answer» B. \[\left( \frac{{{T}_{2}}}{{{T}_{1}}-{{T}_{2}}} \right)\,\,\left( \frac{{{T}_{2}}-{{T}_{3}}}{{{T}_{3}}} \right)\] | |
| 409. |
A single-stage vapour compression refrigeration system cannot be used to produce ultralow temperatures because: |
| A. | Refrigerants for ultra-low temperatures are not available |
| B. | lunbricants for ultra-low temperatures are not available |
| C. | Volumetric efficiency will decrease consider- ably |
| D. | Heat leakage into the system will be excessive |
| Answer» B. lunbricants for ultra-low temperatures are not available | |
| 410. |
Fans used for mechanical draft (induced) cooling towers are: |
| A. | Axial flow type |
| B. | Radial flow type |
| C. | Centrifugal type |
| D. | Propeller type |
| Answer» E. | |
| 411. |
Which one of the following types of expansion valves is suitable for a refrigeration plant operating at constant load? |
| A. | Thermostatic expansion valve |
| B. | Automatic expansion valve |
| C. | Capillary tube |
| D. | None of the above |
| Answer» C. Capillary tube | |
| 412. |
In a centralized air conditioning system, what is the power of a fan directly proportional to? |
| A. | Fan speed |
| B. | \[{{\left( Fan\,\,speed \right)}^{2}}\] |
| C. | \[{{\left( Fan\,\,speed \right)}^{3}}\] |
| D. | \[{{\left( Fan\,\,speed \right)}^{4}}\] |
| Answer» D. \[{{\left( Fan\,\,speed \right)}^{4}}\] | |
| 413. |
Match List-1 with List-11 and select the correct answer using the code given below the lists: List-I (Commercial name of Refrigerant) List-II (Chemical formula of Refrigerant) A. R 11 1. \[CHCl{{F}_{2}}\] B. R 12 2. \[CC{{l}_{2}}{{F}_{2}}\] C. R 13 3. \[CC{{l}_{3}}{{F}_{{}}}\] D. R 22 4. \[Cl{{F}_{3}}\] Codes: |
| A. | A\[\to \]3, B\[\to \]1, C\[\to \]4, D\[\to \]3 |
| B. | A\[\to \]4, B\[\to \]2, C\[\to \]3, D\[\to \]1 |
| C. | A\[\to \]3, B\[\to \]2, C\[\to \]4, D\[\to \]1 |
| D. | A\[\to \]4, B\[\to \]1, C\[\to \]3, D\[\to \]2 |
| Answer» D. A\[\to \]4, B\[\to \]1, C\[\to \]3, D\[\to \]2 | |
| 414. |
Which one of the following is the correct statement? For a specified condenser temperature, the coefficient of performance of a refrigerator, |
| A. | Increases with the increase in the evaporator temperature |
| B. | Decreases with the increase in evaporator temperature |
| C. | is independent of the evaporator temperature |
| D. | is proportional to the square of the evaporator temperature |
| Answer» B. Decreases with the increase in evaporator temperature | |
| 415. |
Which one of the following statements is correct? For a cooling and dehumidification process, the moist air has to be passed through a coil whose temperature is below the: |
| A. | dry-bulb temperature of the air |
| B. | wet-bulb temperature of the air |
| C. | dew-point temperature of the air |
| D. | Critical temperature of the air |
| Answer» D. Critical temperature of the air | |
| 416. |
What is the process represented by the line\[0-1\] shown on the psychrometric chart (0 to 1)? |
| A. | Humidification and heating |
| B. | Humidification and cooling |
| C. | Dehumidification and cooling |
| D. | Dehumidification and heating |
| Answer» E. | |
| 417. |
In an ideal refrigeration (reversed Carnot) cycle, the condenser and evaporator temperatures are \[27{}^\circ C\] and \[-13{}^\circ C\] respectively. The COP of this cycle would be' |
| A. | 6.5 |
| B. | 7.5 |
| C. | 10.5 |
| D. | 15 |
| Answer» B. 7.5 | |
| 418. |
Which one of the following is the correct statement? Sensible heating of moist air will not affect the: |
| A. | Relative humidity |
| B. | Absolute humidity |
| C. | Specific humidity |
| D. | Wet bulb temperature |
| Answer» D. Wet bulb temperature | |
| 419. |
Which one of the following is the correct statement? In domestic air conditioners air undergoes the process of: |
| A. | Sensible cooling |
| B. | Cooling and humidification. |
| C. | Cooling and dehumidification |
| D. | Dehumidification |
| Answer» C. Cooling and dehumidification | |
| 420. |
Which one of the following is the correct statement? Adiabatic saturation process is moist air involves: |
| A. | Cooling and humidification. |
| B. | Cooling and dehumidification |
| C. | Change in dew point temperature. |
| D. | Constant relative humidity. |
| Answer» B. Cooling and dehumidification | |
| 421. |
A refrigerating machine in heat pump mode has a C.O.P. of 4. If it is worked in refrigerating mode with a power input of 3 kW, what is the heat extracted from the food kept in a refrigerator? |
| A. | 180 kJ/min |
| B. | 360 kJ/min |
| C. | 540 kJ/min |
| D. | 720 kJ/min |
| Answer» D. 720 kJ/min | |
| 422. |
The comfort air-conditioning can be obtained by innumerable combinations of DBT and relative humidity. Which one of the following combinations within the comfort zoom recommended to save the energy? |
| A. | Higher DBT and lower relative humidity |
| B. | Lower DBT and lower relative humidity |
| C. | Lower DBT and higher relative humidity |
| D. | Higher DBT and relative humidity |
| Answer» D. Higher DBT and relative humidity | |
| 423. |
During a comfort air conditioning process, the moisture content of the air may start decreasing. Which one of the following is the correct statement? In order to maintain the same level of comfort: |
| A. | WBT should be decreased |
| B. | DBT should be increased |
| C. | Air velocity should be increased |
| D. | Moisture content should be increased |
| Answer» E. | |
| 424. |
Which one of the following is the correct statement? During sensible cooling process for a moist air: |
| A. | Specific humidity will decrease |
| B. | Relative humidity will increase |
| C. | Relative humidity will decrease |
| D. | Specific humidity will increase |
| Answer» B. Relative humidity will increase | |
| 425. |
Which one of the following is the correct statement? When moist air passes through a cooling tower, the process is: |
| A. | Evaporative cooling |
| B. | Adiabatic saturation |
| C. | Cooling and dehumidification |
| D. | Heating and humidification |
| Answer» B. Adiabatic saturation | |
| 426. |
Consider the following refrigerants: 1. Ammonia 2. Carbon dioxide 3. Dichlorodifluoro methane 4. Tetrafluoromethane Which one of the following is the correct order of their boiling points in the descending order? |
| A. | 1 - 2 - 3 - 4 |
| B. | 4 - 3 - 1 - 2 |
| C. | 3 - 1 - 2 - 4 |
| D. | 2 - 4 - 1 - 3 |
| Answer» C. 3 - 1 - 2 - 4 | |
| 427. |
A water chiller with a capacity of 30 tons of refrigeration cools \[20\,{{m}^{3}}/hr\] of water entering at \[12{}^\circ C.\] what is the temperature of water leaving the chiller? |
| A. | \[5{}^\circ C\] |
| B. | \[6{}^\circ C\] |
| C. | \[7{}^\circ C\] |
| D. | \[7.5{}^\circ C\] |
| Answer» E. | |
| 428. |
When \[40{}^\circ C\] and \[25{}^\circ C\] are the dry bulb temperatures of air entering and leaving a cooling coil, then the cooling coil temperature is \[20{}^\circ C.\]What is the bypass factor for the case of sensible cooling? |
| A. | 0.20 |
| B. | 0.25 |
| C. | 0.50 |
| D. | 0.6 |
| Answer» C. 0.50 | |
| 429. |
Consider the following statements pertaining to Room Sensible Heat Ratio (RSHR) line: 1. It is the line drawn on psychrometric chart through the room conditions. 2. Its slope is the ratio of sensible cooling load to room latent heat load. 3. The supply air condition must lie on this line for satisfactory performance. Which of the statements given above are correct? |
| A. | 1, 2 and 3 |
| B. | 1 and 2 |
| C. | 1 and 3 |
| D. | 2 and 3 |
| Answer» D. 2 and 3 | |
| 430. |
In a vapour compression refrigeration cycle, following data are obtained: Ethalpy at suction to the compressor : \[180\,\,kJ/kg\] Ethalpy at discharge from the compressor : \[210\,\,kJ/kg\] Enthalpy at exit from : \[80\,\,kJ/kg\] What is the C.O.P. of the cycle? |
| A. | 5.33 |
| B. | 4.33 |
| C. | 3.33 |
| D. | 2.33 |
| Answer» D. 2.33 | |
| 431. |
An Electrolux system of refrigeration has: |
| A. | No liquid pump |
| B. | One liquid pump |
| C. | Liquid pumps |
| D. | three liquid pumps |
| Answer» B. One liquid pump | |
| 432. |
When the lower temperature is fixed, how can the C.O.P. of a refrigerating machine be improver: |
| A. | By raising the higher temperature |
| B. | By lowering the higher temperature |
| C. | By operating the machine at higher speeds |
| D. | By operating the machine at lower speeds |
| Answer» C. By operating the machine at higher speeds | |
| 433. |
A Bell-Coleman air refrigeration system operates on which one of the following cycles? |
| A. | Reverse Diesel cycle |
| B. | Reverse cannot cycle |
| C. | Reverse Brayton cycle |
| D. | Reverse Otto cycle |
| Answer» D. Reverse Otto cycle | |
| 434. |
If moist air sensibly cooled above its dew point, which of the following statements are correct? 1. Relative humidity decreases 2. Wet bulb temperature decreases, 3. Wet bulb temperature increases 4. Humidity ratio remains constant. Select the correct answer using the codes given below: Codes: |
| A. | 1 and 2 |
| B. | 1 and 3 |
| C. | 3 and 4 |
| D. | 2 and 4 |
| Answer» D. 2 and 4 | |
| 435. |
Which of the features of expansion valves in the following lists are correctly matched? Expansion Device Feature 1. Capillary tube : Chocking 2. Thermostatic Expansion valve : Constant temperature 3. Automatic Expansion valve : Constant degree of superheat 4. Float valve : Mass flow rate of refrigerant is proportional to load Select the correct answer using the codes given below. Codes: |
| A. | 1 and 2 |
| B. | 1 and 3 |
| C. | 1 and 4 |
| D. | 3 and 4 |
| Answer» E. | |
| 436. |
In order to cool and dehumidify a stream of moist air, it must be passed over a coil at a temperature: |
| A. | Which to lies between the dry bulb and wet bulb temperatures of the incoming stream |
| B. | Which lies between the wet bulb and dew point temperatures of the incoming stream |
| C. | Which is lower than the dew point temperature of the incoming stream |
| D. | Of adiabatic saturation of incoming stream |
| Answer» D. Of adiabatic saturation of incoming stream | |
| 437. |
Moist air exists at a pressure of 1.01 bar. The partial pressure and saturation pressure of water vapour are 0.01 bar and 0.02 bar, respectively. What are the relative humidity and humidity ratio of the moist air, respectively? |
| A. | 50% and 0.00622 |
| B. | 100% and 0.0126 |
| C. | 50% and 0.0126 |
| D. | 100% and 0.00622 |
| Answer» B. 100% and 0.0126 | |
| 438. |
When does L.P. cut-off occur in a refrigeration system? |
| A. | If the ambient temperature is low |
| B. | If non-condensable gases are present in the condenser |
| C. | If refrigerant charge is low |
| D. | If lubricating oil gets accumulated-in the condenser |
| Answer» D. If lubricating oil gets accumulated-in the condenser | |
| 439. |
Which one of the following is the most important function of thermostatic expansion valve? |
| A. | To control the degree of superheat |
| B. | To control the evaporator temperature |
| C. | To control the pressure drop |
| D. | To control the evaporator pressure |
| Answer» C. To control the pressure drop | |
| 440. |
A refrigerator storage is supplied with 3600 kg of fish at a temperature of\[27{}^\circ C\]. The fish has to be cooled to \[23{}^\circ C\] for preserving it for a long period without deterioration. The cooling takes place in 10 hours. The specific heat of fish is 2.0 kJ/kg K above freezing point of fish and 0.5 kJ/kg K below freezing point of fish, which is\[-\,3{}^\circ C\]. The latent heal of freezing is 230 kJ/kg. What is the power to drive the plant if the actual COP is half that of the ideal COP? |
| A. | 30 kW |
| B. | 15 kW |
| C. | 12 kW |
| D. | 6 kW. |
| Answer» D. 6 kW. | |
| 441. |
In a regenerative cycle, steam with enthalpy of 3514 kJ/kg is expanded in h.p. turbine to a state corresponding to saturated enthalpy of water equal to 613 kJ/kg. If the pump work requirements in high pressure and low pressure zones are respectively 3 and 1 kJ/kg, amount of heat transferred in boiler is: |
| A. | 2897 kJ/kg |
| B. | 2898 kJ/kg |
| C. | 2904 kJ/kg |
| D. | 2905 kJ/kg |
| Answer» B. 2898 kJ/kg | |
| 442. |
The efficiency of a carnot engine is given as 0.75. If the cycle directions is reversed, what will be the valve of C.O.P. for the carnot refrigerator? |
| A. | 0.27 |
| B. | 0.33 |
| C. | 1.27 |
| D. | 2.33 |
| Answer» C. 1.27 | |
| 443. |
Consider the following statements pertaining to a vapour compression type refrigerator: 1. The condenser rejects heat to the surroundings from the refrigerant. 2. The evaporator absorbs heat from the surroundings to be cooled. 3. Both the condenser and evaporator are heat exchangers with refrigerant as a common medium. 4. The amount of heat exchanged in condenser and evaporator are equal under steady conditions. Which of the above statements are correct? |
| A. | 1 and 2 |
| B. | 1, 2 and 3 |
| C. | 1, 2 and 4 |
| D. | 2, 3 and 4 |
| Answer» C. 1, 2 and 4 | |
| 444. |
In a vapour compression cycle, the refrigerant, immediately after expansion valve is: |
| A. | Saturated liquid |
| B. | sub-cooled liquid |
| C. | dry-vapour |
| D. | wet vapour |
| Answer» E. | |
| 445. |
The main process which takes place in a desert cooler is: |
| A. | Sensible cooling |
| B. | Dehumidification |
| C. | Adiabatic saturation |
| D. | Cooling and dehumidification |
| Answer» D. Cooling and dehumidification | |
| 446. |
A cooling coil with a by-pass factor of 0.1 and apparatus dew point (adp) of \[12{}^\circ C\] comes in contact with air having a dry-bulb temperature of \[38{}^\circ C\] and dew point of \[9{}^\circ C.\] Over the cooling coil, the air would undergo: |
| A. | Sensible cooling |
| B. | Cooling and humidification |
| C. | Cooling and dehumidification |
| D. | Adiabatic saturation |
| Answer» D. Adiabatic saturation | |
| 447. |
The expression, where \[\frac{0.622{{p}_{v}}}{{{p}_{b-}}{{p}_{v}}}\] where \[{{p}_{v}}\,=\] partial pressure of water vapour: \[{{p}_{b}}\,=\] atmospheric barometric pressure, is used for calculating: |
| A. | Relative humidity |
| B. | degree of saturation |
| C. | Humidity ratio |
| D. | pressure of air |
| Answer» D. pressure of air | |
| 448. |
When moist air comes into contact with a waited surface whose temperature is less than the dry-bulb temperature but more than the wet-bulb temperature: |
| A. | Sensible, latent and net heat transfers are from air to surface |
| B. | Both sensible and net heat transfers arc from air to surface but latent neat transfer is from surface to air |
| C. | Sensible heat transfer is from air to surface but both latent and net heat transfer are from surface to air |
| D. | Sensible heat transfer is from surface to air but both latent and net heat transfers arc from air to surface |
| Answer» D. Sensible heat transfer is from surface to air but both latent and net heat transfers arc from air to surface | |
| 449. |
Match List-I with List-II and select the correct answer using the codes given below the Lists: List-I List-II A. Freon 12 1. Centrifugal systems B. Freon 22 2. Low temperature cold storage C. Feron 11 3. Window type units D Ammonia 4. Ice plants Codes: |
| A. | A\[\to \]3, B\[\to \]2, C\[\to \]1, D\[\to \]4 |
| B. | A\[\to \]3, B\[\to \]1, C\[\to \]2, D\[\to \]4 |
| C. | A\[\to \]1, B\[\to \]2, C\[\to \]4, D\[\to \]3 |
| D. | A\[\to \]1, B\[\to \]3, C\[\to \]4, D\[\to \]2 |
| Answer» B. A\[\to \]3, B\[\to \]1, C\[\to \]2, D\[\to \]4 | |
| 450. |
Consider the following statements: 1. If air heated in a closed chamber, its dew point will increase 2. As relative humidity decreases the difference between the wet-bulb temperature and dew point will increase 3. In spray humidification process, the enthalpy of air will decrease 4. The dew-point temperature is always an indication of moisture content of the air |
| A. | 1 and 2 |
| B. | 2 and 4 |
| C. | 1 and 3 |
| D. | 3 and 4 |
| Answer» E. | |