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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.
| 451. |
The refrigerant-12 (R-12) used in vapour compression refrigeration system is: |
| A. | \[CHCl{{F}_{2}}\] |
| B. | \[CC{{l}_{2}}{{F}_{2}}\] |
| C. | \[CHC{{l}_{2}}F\] |
| D. | \[CCl{{F}_{2}}\] |
| Answer» C. \[CHC{{l}_{2}}F\] | |
| 452. |
A Carnot refrigerator works between the temperatures of 200 K and 300 K. If the refrigerator receives 1 k W of heat, the work requirement will be: |
| A. | 0.5 k W |
| B. | 0.67 k W |
| C. | 1.5 k W |
| D. | 3 k W |
| Answer» B. 0.67 k W | |
| 453. |
Consider the following steps: 1. Starting of compressor. 2. Starting of cooling tower pump 3. Starting of chiller water pump 4. Starting of blower motor of cooling coil The correct sequence of these steps in the starting of a central air conditioning plant using chilled water cooling coil, is: |
| A. | 3, 1, 4, 2 |
| B. | 1, 3, 2, 4 |
| C. | 3, 2, 1, 4 |
| D. | 1, 3, 4, 2 |
| Answer» D. 1, 3, 4, 2 | |
| 454. |
Consider the following statements: 1. In Freon 22 system, moisture choking generally does not occur 2. Freon 11 is mainly used in large capacity air- conditioning plants with centrifugal compressors. 3. Presence of lubricating oil in evaporator will increase the heat transfer coefficient. 4. Refrigerants that are completely miscible with oil, do not cause oil choking. Of these statements: |
| A. | 1, 2 and 3 are correct |
| B. | 1, 2 and 4 are correct |
| C. | 2, 3 and 4 are correct |
| D. | 1, 3 and 4 are correct |
| Answer» B. 1, 2 and 4 are correct | |
| 455. |
Match List-I with List-II and select the correct answer using the codes given below the lists: List-I (Refrigerant) List-II (Designation) A. Dichlorodifluoromenthane 1. R 718 B. Water 2. R 22 C. Methyl chloride 3. R 40 D. Monochlorodifluoromethane 4. R 12 Codes |
| A. | A\[\to \]1, B\[\to \]4, C\[\to \]2, D\[\to \]3 |
| B. | A\[\to \]1, B\[\to \]4, C\[\to \]3, D\[\to \]2 |
| C. | A\[\to \]4, B\[\to \]1, C\[\to \]3, D\[\to \]2 |
| D. | A\[\to \]4, B\[\to \]1, C\[\to \]2, D\[\to \]3 |
| Answer» E. | |
| 456. |
Consider the following statements: Dry compression in reciprocating compressor is preferred because it: 1. Prevents valve damage. 2. Enables use of thermostatic exansion valve 3. Minimizes irreversibilites in the compressor. 4. Prevents washing out of the lubricating oil from cylinder walls. Of these statements: |
| A. | 1 and 2 are correct |
| B. | 2 and 3 are correct |
| C. | 1 and 4 are correct |
| D. | 3 and 4 are correct |
| Answer» D. 3 and 4 are correct | |
| 457. |
If wet bulb depression is equal to the sum of range and approach of a cooling tower, then the water: |
| A. | Inlet temperature is equal to the wet bulb temperature of ambient air |
| B. | Outlet temperature is equal to the wet bulb temperature of ambient air |
| C. | Inlet temperature is equal to dry bulb temperature of ambient air |
| D. | Outlet temperature is equal to dry bulb temperature of ambient air |
| Answer» D. Outlet temperature is equal to dry bulb temperature of ambient air | |
| 458. |
Consider the following statements: Effective temperature is not a true comfort index because 1. Discomfort may be experienced at extremely high or low humidity. 2. The radiation effect of surrounding surfaces has not been taken into account. 3. It presumes the absence of drafts. Of these statements: |
| A. | 1, 2 and 3 are correct |
| B. | 1 and 2 are correct |
| C. | 1 and 3 are correct |
| D. | 2 and 3 are correct |
| Answer» B. 1 and 2 are correct | |
| 459. |
A valve which maintains a constant degree of superheat at the end of the evaporator coil, is called: |
| A. | Automatic expansion valve |
| B. | High side float valve |
| C. | Thermostatic expansion valve |
| D. | Low side float valve |
| Answer» D. Low side float valve | |
| 460. |
While designing the refrigeration system of an aircraft prime consideration is that the: |
| A. | System has high COP |
| B. | H.P. / ton is low |
| C. | Weight of refrigerant circulated in the system is the low |
| D. | Weight of the refrigeration equipment is low |
| Answer» E. | |
| 461. |
In a vapour compression refrigeration plant, the refrigerant leaves the evaporator at 195 kJ/kg and the condenser at 65 kJ/kg. For every kg of refrigerant the plant can supply per second a cooling load of: |
| A. | 70 kW |
| B. | 100 kW |
| C. | 130 kW |
| D. | 160 kW |
| Answer» D. 160 kW | |
| 462. |
By pass factor for a cooling coil: |
| A. | Increases with increase in velocity of air passing through it |
| B. | Decrease with increase in velocity of air passing through it |
| C. | Remains unchanged with increase in velocity of air passing through it |
| D. | May increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering |
| Answer» B. Decrease with increase in velocity of air passing through it | |
| 463. |
A thermostatic expansion valve in a refrigeration system: |
| A. | Ensures the evaporator completely filled with refrigerant of the load |
| B. | is suitable only for constant load system |
| C. | Maintains different temperatures in evaporator |
| D. | None of the above. |
| Answer» B. is suitable only for constant load system | |
| 464. |
If air is passed through a solid chemical absorbent, the psychrometic process followed is: |
| A. | Heating and dehumidification with the bulb temperature remaining fairly constant |
| B. | Cooling and dehumidification |
| C. | Dehumidification with sharp rise in wet bulb temperature |
| D. | Dehumidification at constant dry bulb temperature. |
| Answer» B. Cooling and dehumidification | |
| 465. |
Which of the following refrigerant has the maximum ozone depletion in the stratosphere? |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | Fluorine |
| Answer» E. | |
| 466. |
Evaporative regulation of body temperature fails when the body temperature is: |
| A. | More than wet bulb temperature but less than dry bulb temperature |
| B. | More than dew point but less than wet bulb Temperature |
| C. | More than dew point but less than dry bulb Temperature |
| D. | Less than dew point |
| Answer» D. Less than dew point | |
| 467. |
The operating temperature of a cold storage is \[-2{}^\circ C,\] Heat leakage form the surrounding is 30 kW for the ambient temperature of \[40{}^\circ C.\] the actual COP of the refrigeration plant used is one fourth that of an ideal plant working between the same temperatures. The power required to drive the plant is: |
| A. | 1.86 kW |
| B. | 3.72 kW |
| C. | 7.44 kW |
| D. | 18.60 kW |
| Answer» E. | |
| 468. |
In the case of sensible cooling of air, the coil efficiency is given by: (BPF = Bypass factor) |
| A. | \[BPF-1\] |
| B. | \[1-BPF\] |
| C. | \[\frac{1}{BPF}\] |
| D. | \[1+BPF\] |
| Answer» C. \[\frac{1}{BPF}\] | |
| 469. |
A human body feels comfortable when the heat produced by the metabolism of human body is equal to the: |
| A. | Heat dissipated to the surroundings |
| B. | Heat stored in the human body |
| C. | Sum of A and B |
| D. | Difference of A and B |
| Answer» B. Heat stored in the human body | |
| 470. |
Effective temperature is that temperature of saturated air which gives the same degree of comfort as the air at given: |
| A. | DBT, WBT and incidental solar radiation |
| B. | WBT, incidental solar radiation and air flow rate |
| C. | DBT, sol-air temperature and air flow rate |
| D. | DBT, WBT and air flow rate |
| Answer» E. | |
| 471. |
Moist air is a mixture of dry air and water vapour. Hence, three independent intrinsic thermodynamic three independent intrinsic thermodynamic properties are required to fix its thermodynamic state. While using psychrometric chart, however, only two thermodynamic properties are needed since, psychrometric chart: |
| A. | Is an approximation to actual properties |
| B. | Assumes that both water vapour and dry air behave like perfect gases |
| C. | Is drawn for actual properties of water vapour and dry air |
| D. | Is drawn for a fixed pressure |
| Answer» E. | |
| 472. |
If a sample of moist air of 50% relative humidity at atmospheric pressure is isothermally compressed to a pressure of two atmospheres, then: |
| A. | Its relative humidity will reduce to 25% |
| B. | Its relative humidity will remain unchanged |
| C. | The sample of air will become saturated |
| D. | Saturation pressure will increase to twice the value |
| Answer» D. Saturation pressure will increase to twice the value | |
| 473. |
If the specific heats of dry air and water vapour are \[1.00\,\,kJ/kg\,-K\] and \[1.88\,\,kJ/kg\,-K\]respectively and the humidity ratio is 0.011, then the specific heat of moist air at \[25{}^\circ C\] and 50% relative humidity will be |
| A. | \[1.0207\,\,kJ/kg-K\] |
| B. | \[1.869\,\,kJ/kg-K\] |
| C. | \[1.891\,\,kJ/kg-K\] |
| D. | \[0.9793\,\,kJ/kg-K\] |
| Answer» B. \[1.869\,\,kJ/kg-K\] | |
| 474. |
Which of the following crystal filter is used only at the higher frequencies? |
| A. | Half lattice |
| B. | Ladder |
| C. | Crystal gale |
| D. | None of these |
| Answer» C. Crystal gale | |
| 475. |
Which of the following noise is of great importance at high frequencies? |
| A. | Flicker noise |
| B. | Transit-time noise |
| C. | Short noise |
| D. | None of these |
| Answer» C. Short noise | |
| 476. |
The value of a resistor creating thermal noise is doubled. The noise power generated will be |
| A. | halved |
| B. | doubled |
| C. | unchanged |
| D. | none of these |
| Answer» D. none of these | |
| 477. |
Radar gives target's: |
| A. | Range |
| B. | Size |
| C. | Velocity and range |
| D. | Color |
| Answer» D. Color | |
| 478. |
In a radio receiver the noise is generally increased by |
| A. | power supply |
| B. | mixer |
| C. | local oscillator |
| D. | none of these |
| Answer» C. local oscillator | |
| 479. |
Radar can be used in |
| A. | satellites |
| B. | space research |
| C. | solar system |
| D. | none of these |
| Answer» B. space research | |
| 480. |
Radar is used by ships, large and small, for navigation especially in |
| A. | bad weather |
| B. | with poor visibility |
| C. | [a] and [b] |
| D. | none of these |
| Answer» D. none of these | |
| 481. |
Radar can be used for the exploration of |
| A. | solar system |
| B. | interplanetary space |
| C. | both [a] and [b] |
| D. | none of these |
| Answer» C. both [a] and [b] | |
| 482. |
Radar is used by military for |
| A. | surveillance |
| B. | safety |
| C. | weapons |
| D. | none of these |
| Answer» B. safety | |
| 483. |
The Ballistic Missile Early Warning Systems radar is used to detect the track of |
| A. | missiles |
| B. | ballistic missiles |
| C. | intercontinental ballistic missiles |
| D. | both [a] and [b] |
| Answer» D. both [a] and [b] | |
| 484. |
Hartley law states that |
| A. | the maximum rate of information transmission depends on the depth of modulation |
| B. | me maximum rate of information transmission depends on the channel bandwidth. |
| C. | redundancy is essential |
| D. | only binary codes may be used. |
| Answer» C. redundancy is essential | |
| 485. |
When installed in ships or high flying aero planes, radars can be used under all weather conditions to find the positions of mountains and |
| A. | icebergs in the sea |
| B. | shore lines |
| C. | lakes etc. |
| D. | [a], [b] and [c] |
| Answer» E. | |
| 486. |
In Chain Home Low System, the target ranges were more than |
| A. | 100 km |
| B. | 85 km |
| C. | 65 km |
| D. | 75 km |
| Answer» B. 85 km | |
| 487. |
The techniques developed for radar have paved the way of more advanced research in |
| A. | solar system |
| B. | microwave |
| C. | spectroscopy |
| D. | none of these |
| Answer» D. none of these | |
| 488. |
Distance Early Warning (DEW) radar/radars is/are used to detect the |
| A. | aircrafts |
| B. | enemies |
| C. | both [a] and [b] |
| D. | none of these |
| Answer» B. enemies | |
| 489. |
The performance of radar is unaffected by |
| A. | darkness |
| B. | fog |
| C. | rain |
| D. | [a], [b] and [c] |
| Answer» E. | |
| 490. |
Chain Home Low System was first introduced in |
| A. | 1952 |
| B. | 1959 |
| C. | 1964 |
| D. | 1972 |
| Answer» C. 1964 | |
| 491. |
In Chain Home Low System, same aexial was used for |
| A. | transmission and modulation |
| B. | reception and modulation |
| C. | transmission and reception |
| D. | none of these |
| Answer» D. none of these | |
| 492. |
Radar can be used to guide |
| A. | vehicles |
| B. | space vehicles |
| C. | the science |
| D. | none of these |
| Answer» C. the science | |
| 493. |
Radars are used in |
| A. | detection |
| B. | tracking of weather |
| C. | both [a] and [c] |
| D. | none of these |
| Answer» D. none of these | |
| 494. |
Surveillance raders detect and locate hostile targets for the purpose of |
| A. | military action |
| B. | proper military action |
| C. | war |
| D. | none of these |
| Answer» C. war | |
| 495. |
The ionosphere consists of |
| A. | positively charged layer |
| B. | negatively charged layer |
| C. | both [a] and [b] |
| D. | none of these |
| Answer» C. both [a] and [b] | |
| 496. |
Chain Home System was designed for the location and detection of |
| A. | enemy |
| B. | approaching aircraft bombers |
| C. | both [a] and [b] |
| D. | none of these |
| Answer» C. both [a] and [b] | |
| 497. |
Radars can be used under |
| A. | bad weather conditions |
| B. | good weather conditions |
| C. | all weather conditions |
| D. | none of these |
| Answer» D. none of these | |
| 498. |
The Chain Home Low System is effective within the rana of....... from the target, |
| A. | 5 km |
| B. | 7 km |
| C. | 10 km |
| D. | 15 km |
| Answer» B. 7 km | |
| 499. |
Radar is |
| A. | a mechanical device |
| B. | an electrical device |
| C. | a pneumatic device |
| D. | an electromagnetic device |
| Answer» E. | |
| 500. |
The disadvantage of tuned radio frequency receiver is |
| A. | band width variation |
| B. | in stability |
| C. | both [a] and [b] |
| D. | none of these |
| Answer» D. none of these | |