MCQOPTIONS
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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.
| 351. |
The rate of heat flow through a body is . The term x/kA is known as |
| A. | thermal coefficient |
| B. | thermal resistance |
| C. | thermal conductivity |
| D. | none of these |
| Answer» C. thermal conductivity | |
| 352. |
During a refrigeration cycle, heat is rejected by the refrigerant in a |
| A. | compressor |
| B. | condenser |
| C. | evaporator |
| D. | expansion valve |
| Answer» C. evaporator | |
| 353. |
Nusselt number (NN) is given by |
| A. | NN = hl/k |
| B. | NN = μ cp/k |
| C. | NN = ρ V l /μ |
| D. | NN = V²/t.cp |
| Answer» B. NN = μ cp/k | |
| 354. |
In case of solids, the heat transfer takes place according to radiation. |
| A. | Correct |
| B. | Incorrect |
| C. | - |
| D. | - |
| Answer» C. - | |
| 355. |
The relative humidity decreases as air gets wet. |
| A. | True |
| B. | False |
| C. | - |
| D. | - |
| Answer» B. False | |
| 356. |
A water cooled condenser operates at a __________ condensing temperature than an air-cooled condenser. |
| A. | higher |
| B. | lower |
| C. | - |
| D. | - |
| Answer» C. - | |
| 357. |
The critical radius is the insulation radius at which the resistance to heat flow is |
| A. | maximum |
| B. | minimum |
| C. | zero |
| D. | none of these |
| Answer» C. zero | |
| 358. |
During sensible cooling of air __________ decreases. |
| A. | wet bulb temperature |
| B. | relative humidity |
| C. | dry bulb temperature |
| D. | specific humidity |
| Answer» D. specific humidity | |
| 359. |
The subcooling in a refrigeration cycle |
| A. | does not alter C.O.P. |
| B. | increases C.O.P. |
| C. | decreases C.O.P. |
| D. | none of these |
| Answer» C. decreases C.O.P. | |
| 360. |
A refrigeration system |
| A. | removes heat from a low temperature body and delivers it to a high temperature body |
| B. | removes heat from a high temperature body and delivers it to a low temperature body |
| C. | rejects energy to a low temperature body |
| D. | none of the above |
| Answer» B. removes heat from a high temperature body and delivers it to a low temperature body | |
| 361. |
The coefficient of performance of Heat Pump is always __________ one. |
| A. | equal to |
| B. | less than |
| C. | greater than |
| D. | - |
| Answer» D. - | |
| 362. |
Degree of saturation or percentage humidity is |
| A. | the mass of water vapour present in 1 m 3 of dry air |
| B. | the mass of water vapour present in 1 kg of dry air |
| C. | the ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure. |
| D. | 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 |
| Answer» D. 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 | |
| 363. |
The thickness of thermal and hydrodynamic boundary layer is equal if Prandtl number is |
| A. | equal to one |
| B. | greater than one |
| C. | less than one |
| D. | equal to Nusselt number |
| Answer» B. greater than one | |
| 364. |
During adiabatic saturation process on unsaturated air __________ remains constant. |
| A. | relative humidity |
| B. | dew point temperature |
| C. | dry bulb temperature |
| D. | wet bulb temperature |
| Answer» E. | |
| 365. |
Thermal conductivity of water __________ with rise in temperature. |
| A. | remains same |
| B. | decreases |
| C. | increases |
| D. | may increase or decrease depending upon temperature |
| Answer» E. | |
| 366. |
The heat transfer by radiation __________ a medium. |
| A. | requires |
| B. | does not require |
| C. | - |
| D. | - |
| Answer» C. - | |
| 367. |
An electrolux refrigerator is called a __________ absorption system. |
| A. | single fluid |
| B. | two fluids |
| C. | three fluids |
| D. | - |
| Answer» D. - | |
| 368. |
The heat transfer takes place according to |
| A. | Zeroth law of thermodynamics |
| B. | First law of thermodynamics |
| C. | Second law of thermodynamics |
| D. | Kirchhoff's law |
| Answer» D. Kirchhoff's law | |
| 369. |
For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of |
| A. | copper |
| B. | aluminium |
| C. | steel |
| D. | brass |
| Answer» D. brass | |
| 370. |
In a psychrometric process, the sensible heat added is 30 kJ/s and the latent heat added is 20 kJ/s. The sensible heat factor for the process will be |
| A. | 0.3 |
| B. | 0.6 |
| C. | 0.67 |
| D. | 1.5 |
| Answer» C. 0.67 | |
| 371. |
The condition of refrigerant after leaving the compressor and before entering the condenser is superheated vapour. |
| A. | Yes |
| B. | No |
| C. | - |
| D. | - |
| Answer» B. No | |
| 372. |
The total radiation from a black body per second per unit area is __________ fourth power of the absolute temperature. This statement is known as Stefan-Boltzmann law. |
| A. | equal to |
| B. | directly proportional to |
| C. | inversely proportional to |
| D. | - |
| Answer» C. inversely proportional to | |
| 373. |
Thermal diffusivity is a |
| A. | function of temperature |
| B. | physical property of a substance |
| C. | dimensionless parameter |
| D. | all of these |
| Answer» C. dimensionless parameter | |
| 374. |
The wet bulb temperature lines, on the psychrometric chart, are curved lines. |
| A. | True |
| B. | False |
| C. | - |
| D. | - |
| Answer» C. - | |
| 375. |
The process of heat transfer from a hot body to a cold body, in a straight line, without affecting the intervening medium, is called radiation. |
| A. | True |
| B. | False |
| C. | - |
| D. | - |
| Answer» B. False | |
| 376. |
The optimum effective temperature for human comfort is |
| A. | higher in winter than in summer |
| B. | lower in winter than in summer |
| C. | same in winter and summer |
| D. | not dependent on season |
| Answer» C. same in winter and summer | |
| 377. |
As relative humidity decreases, the dew point temperature will be __________ wet bulb temperature. |
| A. | same as |
| B. | lower than |
| C. | higher man |
| D. | - |
| Answer» C. higher man | |
| 378. |
In aqua-ammonia and Lithium-bromide water absorption refrigeration systems, the refrigerants are respectively |
| A. | water and water |
| B. | water and lithium bromide |
| C. | ammonia and lithium bromide |
| D. | ammonia and water |
| Answer» E. | |
| 379. |
The heat transfer by conduction through a thick sphere is same as through a thick cylinder. |
| A. | True |
| B. | False |
| C. | - |
| D. | - |
| Answer» C. - | |
| 380. |
The relative humidity is defined as |
| A. | the mass of water vapour present in 1 m 3 of dry air |
| B. | the mass of water vapour present in 1 kg of dry air |
| C. | the ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure. |
| D. | 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 |
| Answer» E. | |
| 381. |
According to Dalton's law of partial pressures, (where p b = Barometric pressure, p a = Partial pressure of dry air, and p v = Partial pressure of water vapour) |
| A. | P b = p a - p v |
| B. | P b = p a + p v |
| C. | P b = p a x p v |
| D. | P b = p a / p v |
| Answer» C. P b = p a x p v | |
| 382. |
The difference between dry bulb temperature and wet bulb temperature, is called |
| A. | dry bulb depression |
| B. | wet bulb depression |
| C. | dew point depression |
| D. | degree of saturation |
| Answer» C. dew point depression | |
| 383. |
Defrosting of a refrigerator may be done by stopping the compressor for a short period. |
| A. | Correct |
| B. | Incorrect |
| C. | - |
| D. | - |
| Answer» B. Incorrect | |
| 384. |
The by-pass factor for a cooling coil |
| A. | increases with increase in velocity of air passing through it |
| B. | decreases 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. decreases with increase in velocity of air passing through it | |
| 385. |
In a refrigerating machine, heat rejected is __________ heat absorbed. |
| A. | equal to |
| B. | less than |
| C. | greater than |
| D. | - |
| Answer» D. - | |
| 386. |
The humidity ratio or specific humidity is the mass of water vapour present in |
| A. | 1 m 3 of wet air |
| B. | 1 m 3 of dry air |
| C. | 1 kg of wet air |
| D. | 1 kg of dry air |
| Answer» E. | |
| 387. |
In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the |
| A. | Reynold's number |
| B. | Grashoff's number |
| C. | Reynold's number, Grashoff's number |
| D. | Prandtl number, Grashoff's number |
| Answer» E. | |