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MCQOPTIONS
This section includes 387 Mcqs, each offering curated multiple-choice questions to sharpen your Automobile Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
While designing the refrigeration system of an aircraft, the prime consideration is that the |
| A. | system has high C.O.P. |
| B. | power per TR is low |
| C. | mass of refrigerant circulated in the system is low |
| D. | mass of the refrigeration equipment is low |
| Answer» E. | |
| 302. |
The highest thermal diffusivity is of |
| A. | iron |
| B. | lead |
| C. | concrete |
| D. | wood |
| Answer» C. concrete | |
| 303. |
Radiation is the process of heat transfer in which heat flows from a __________ , in a straight line, without affecting the intervening medium. |
| A. | cold body to hot body |
| B. | hot body to cold body |
| C. | smaller body to larger body |
| D. | larger body to smaller body |
| Answer» C. smaller body to larger body | |
| 304. |
A Bell Coleman refrigerator working on dense air system as compared to open air system, for the same range of temperature, results in higher coefficient of performance. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 305. |
During sensible heating of air __________ decreases. |
| A. | wet bulb temperature |
| B. | relative humidity |
| C. | dry bulb temperature |
| D. | specific humidity |
| Answer» C. dry bulb temperature | |
| 306. |
A refrigerating system operating on reversed Brayton refrigeration cycle is used for maintaining 250 K. If the temperature at the end of constant pressure cooling is 300 K and rise in the temperature of air in the refrigerator is 50 K, then the net work of compression will be (assume air as working substance with cp = 1 kJ/kg) |
| A. | 25 kJ/kg |
| B. | 50 kJ/kg |
| C. | l00 kJ/kg |
| D. | 125 kJ/kg |
| Answer» C. l00 kJ/kg | |
| 307. |
The heat rejection factor (HRF) is given by |
| A. | 1 + C.O.P |
| B. | 1 - C.O.P. |
| C. | 1 + (1/C.O.P) |
| D. | 1 - (1/C.O.P) |
| Answer» D. 1 - (1/C.O.P) | |
| 308. |
Which of the following refrigerant has the maximum ozone depletion potential in the stratophere? |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | Flourine |
| Answer» E. | |
| 309. |
Moisture should be removed from refrigerants to avoid |
| A. | freezing at the expansion valve |
| B. | restriction to refrigerant flow |
| C. | corrosion of steel plates |
| D. | all of these |
| Answer» E. | |
| 310. |
The __________ point of ammonia is -77.7°C. |
| A. | freezing |
| B. | boiling |
| C. | Can't say |
| D. | None of these |
| Answer» B. boiling | |
| 311. |
The amount of heat flow through a body by conduction is |
| A. | directly proportional to the surface area of the body |
| B. | directly proportional to the temperature difference on the two faces of the body |
| C. | inversely proportional to the thickness of the body |
| D. | all of the above |
| Answer» E. | |
| 312. |
The relative humidity lines on a psychrometric chart are |
| A. | vertical and uniformly spaced |
| B. | horizontal and uniformly spaced |
| C. | horizontal and non-uniformly spaced |
| D. | curved lines |
| Answer» E. | |
| 313. |
For unsaturated air, the dew point temperature is __________ wet bulb temperature. |
| A. | equal to |
| B. | less than |
| C. | more than |
| D. | None of these |
| Answer» C. more than | |
| 314. |
The specific humidity during humidification process |
| A. | remains constant |
| B. | increases |
| C. | decreases |
| D. | None of these |
| Answer» C. decreases | |
| 315. |
Dew point temperature corresponds to the saturation temperature of vapour at its partial pressure. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 316. |
The sulphur sticks, in case of leakage of ammonia refrigerant, gives white smoke. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 317. |
For large tonnage (more than 200 TR) air-conditioning applications, the compressor recommended is |
| A. | reciprocating |
| B. | rotating |
| C. | centrifugal |
| D. | screw |
| Answer» D. screw | |
| 318. |
The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure, is called |
| A. | humidity ratio |
| B. | relative humidity |
| C. | absolute humidity |
| D. | degree of saturation |
| Answer» C. absolute humidity | |
| 319. |
Environmental protection agencies advice against the use of chloro-fluoro-carbon refrigerants since |
| A. | these react with water vapour and cause acid rain |
| B. | these react with plants and cause green-house effect |
| C. | these react with oxygen and cause its depletion |
| D. | these react with ozone layer |
| Answer» E. | |
| 320. |
The mass of water vapour present in __________ is called absolute humidity. |
| A. | 1 m³ of wet air |
| B. | 1 m³ of dry air |
| C. | 1 kg of wet air |
| D. | 1 kg of dry air |
| Answer» C. 1 kg of wet air | |
| 321. |
The process of heat transfer from one particle of the body to another by the actual motion of the heated particles, is called |
| A. | conduction |
| B. | convection |
| C. | radiation |
| D. | None of these |
| Answer» C. radiation | |
| 322. |
The rato of energy transferred by convection to that by conduction is called |
| A. | Stanton number |
| B. | Nusselt number |
| C. | Biot number |
| D. | Peclet number |
| Answer» C. Biot number | |
| 323. |
The formation of frost on cooling coils in a refrigerator |
| A. | increases heat transfer |
| B. | improves C.O.P. of the system |
| C. | increases power consumption |
| D. | reduces power consumption |
| Answer» D. reduces power consumption | |
| 324. |
The difference between dry bulb temperature and dew point temperature, is called |
| A. | dry bulb depression |
| B. | wet bulb depression |
| C. | dew point depression |
| D. | degree of saturation |
| Answer» D. degree of saturation | |
| 325. |
Which of the following refrigerant is highly toxic and flammable? |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | R-12 |
| Answer» B. Carbon dioxide | |
| 326. |
In a lithium bromide absorption refrigeration system |
| A. | lithium bromide is used as a refrigerant and water as an absorbent |
| B. | water is used as a refrigerant and lithium bromide as an absorbent |
| C. | ammonia is used as a refrigerant and lithium bromide as an absorbent |
| D. | none of the above |
| Answer» C. ammonia is used as a refrigerant and lithium bromide as an absorbent | |
| 327. |
The automobile radiator is a heat exchanger of |
| A. | parallel flow type |
| B. | counter flow type |
| C. | cross flow type |
| D. | regenerator type |
| Answer» D. regenerator type | |
| 328. |
The ratio of actual heat transfer to the maximum possible heat transfer is known as heat exchanger effectiveness. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 329. |
The wave length of the radiation emitted depends only on the temperature and is independent of the material of the body. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 330. |
The reciprocating refrigerant compressors are very suitable for |
| A. | small displacements and low condensing pressures |
| B. | large displacements and high condensing pressures |
| C. | small displacements and high condensing pressures |
| D. | large displacements and low condensing pressures |
| Answer» D. large displacements and low condensing pressures | |
| 331. |
The coefficient of performance (C.O.P.) is the reciprocal of the efficiency of a heat engine. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 332. |
The unit of Stefan-Boltzmann constant is |
| A. | Watt/mK |
| B. | Watt/m²K² |
| C. | Watt/m²K⁴ |
| D. | Watt/mK² |
| Answer» D. Watt/mK² | |
| 333. |
The leakage in a refrigeration system using ammonia is detected by |
| A. | halide torch |
| B. | sulphur sticks |
| C. | soap and water |
| D. | all of these |
| Answer» C. soap and water | |
| 334. |
Pressure of water vapour is given by |
| A. | 0.622 Pv/ (Pb - Pv) |
| B. | μ/[1 - (1 - μ) (Ps/Pb)] |
| C. | [Pv (Pb - Pd)]/ [Pd (Pb - Pv)] |
| D. | none of these |
| Answer» E. | |
| 335. |
The sensible heat factor during cooling and dehumidification process is given by (where h1 = Enthalpy of air entering the cooling coil, h2 = Enthalpy of air leaving the cooling coil, and hA = Enthalpy of air at the end of dehumidification process) |
| A. | (hA - h2)/ (h1 - h2) |
| B. | (h2 - hA)/ (h1 - h2) |
| C. | (h1 - h2)/ (hA - h2) |
| D. | (hA - h1)/ (h2 - h1) |
| Answer» B. (h2 - hA)/ (h1 - h2) | |
| 336. |
The C.O.P. of an absorption type refrigerator is given by (where T1 = Temperature at which the working substance receives heat, T2 = Temperature of cooling water, and T3 = Evaporator temperature) |
| A. | [T₁ (T₂ - T₃)] / [T₃ (T₁ - T₂)] |
| B. | [T₃ (T₁ - T₂)]/ [T₁ (T₂ - T₃)] |
| C. | [T₁ (T₁ - T₂)] / [T₃ (T₂ - T₃)] |
| D. | [T₃ (T₂ - T₃)] / [T₁ (T₁ - T₂)] |
| Answer» C. [T₁ (T₁ - T₂)] / [T₃ (T₂ - T₃)] | |
| 337. |
The power per tonne of refrigeration is |
| A. | 3.5/C.O.P. |
| B. | C.O.P/3.5 |
| C. | 3.5 x C.O.P. |
| D. | none of these |
| Answer» B. C.O.P/3.5 | |
| 338. |
The natural convection air cooled condensers are used in |
| A. | domestic refrigerators |
| B. | water coolers |
| C. | room air conditioners |
| D. | all of these |
| Answer» B. water coolers | |
| 339. |
The central air conditioning system has __________ overall efficiency as compared to individual systems. |
| A. | same |
| B. | lower |
| C. | higher |
| D. | None of these |
| Answer» D. None of these | |
| 340. |
When α is absorptivity, ρ is reflectivity and τ is transmittivity, then for a diathermanous body, |
| A. | α = 1, ρ = 0 and τ = 0 |
| B. | α = 0, ρ = 1 and τ = 0 |
| C. | α = 0, ρ = 0 and τ = 1 |
| D. | α + ρ = 1 and τ = 0 |
| Answer» E. | |
| 341. |
Which of the following represents a heat pump? |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 342. |
During sensible heating of air, specific humidity remains constant. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 343. |
R-11 has the highest critical point temperature. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 344. |
The transfer of heat by molecular collision is known as |
| A. | conduction |
| B. | convection |
| C. | radiation |
| D. | none of these |
| Answer» B. convection | |
| 345. |
In a domestic vapour compression refrigerator, the refrigerant commonly used is |
| A. | CO₂ |
| B. | Ammonia |
| C. | R-12 |
| D. | all of these |
| Answer» D. all of these | |
| 346. |
The cooling system used for supersonic aircrafts and rockets is |
| A. | simple air cooling system |
| B. | boot-strap air cooling system |
| C. | reduced ambient air cooling system |
| D. | regenerative air cooling system |
| Answer» E. | |
| 347. |
The water, alcohol and ammonia have same refrigerating effect at different altitudes. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 348. |
The mass of water vapour present in 1 kg of dry air, is called humidity ratio. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 349. |
The temperature rise, between the condenser outlet and expansion valve in ammonia vapour compression system, should be as low as possible. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 350. |
The thermostatic expansion valve is also called |
| A. | constant pressure valve |
| B. | constant temperature valve |
| C. | constant superheat valve |
| D. | none of these |
| Answer» D. none of these | |