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.
| 1. |
The absolute humidity is the mass of water vapour present in 1 m3 of dry air. |
| A. | Agree |
| B. | Disagree |
| Answer» B. Disagree | |
| 2. |
When tc1 and tc2 are the temperatures of cold fluid at entry and exit respectively and th1 and th2 are the temperatures of hot fluid at entry and exit point, and cold fluid has lower heat capacity rate as compared to hot fluid, then effectiveness of the heat exchanger is given by |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» E. | |
| 3. |
An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m2). The critical thickness of insulation will be |
| A. | 25 mm |
| B. | 40 mm |
| C. | 160 mm |
| D. | 800 mm |
| Answer» B. 40 mm | |
| 4. |
In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the |
| A. | expansion valve to the evaporator |
| B. | evaporator to the thermostat |
| C. | condenser to the expansion valve |
| D. | condenser to the evaporator |
| Answer» E. | |
| 5. |
According to Prevost's theory of exchanges, every body irrespective of its temperature continuously emit heat radiations to the surrounding bodies and at the same time receives heat radiations from the surrounding bodies. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 6. |
The heating of air, without any change in its specific humidity, is known as sensible heating. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 7. |
The total pressure exerted by the mixture of air and water vapour is equal to the sum of pressures which each constituent would exert, if it occupied the same space by itself. This statement is called |
| A. | Kinetic theory of gases |
| B. | Newton's law of gases |
| C. | Dalton's law of partial pressures |
| D. | Avogadro's hypothesis |
| Answer» D. Avogadro's hypothesis | |
| 8. |
In a pressure enthalpy chart, the space between the saturated liquid line and saturated vapour line, represents sub-cooled liquid region. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 9. |
Thermal conductivity of solid metals __________ with rise in temperature. |
| A. | remains same |
| B. | decreases |
| C. | increases |
| D. | None of these |
| Answer» C. increases | |
| 10. |
Wet bulb temperature indicates the moisture content in air. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 11. |
When the temperature of the surrounding is higher than the temperature of the body, then the heat loss by convection from the body to the surrounding will be |
| A. | positive |
| B. | negative |
| C. | zero |
| D. | none of these |
| Answer» C. zero | |
| 12. |
During sub-cooling, sensible heat from a liquid refrigerant is removed. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 13. |
R-12 has the __________ freezing point. |
| A. | lowest |
| B. | highest |
| C. | Can't say |
| D. | None of these |
| Answer» B. highest | |
| 14. |
The specific humidity during dehumidification process |
| A. | remains constant |
| B. | increases |
| C. | decreases |
| D. | None of these |
| Answer» D. None of these | |
| 15. |
The comfort conditions in air conditioning are at (where DBT = Dry bulb temperature, and RH = Relative humidity) |
| A. | 25°C DBT and 100% RH |
| B. | 20°C DBT and 80% RH |
| C. | 22°C DBT and 60% RH |
| D. | 25°C DBT and 40% RH |
| Answer» D. 25°C DBT and 40% RH | |
| 16. |
In a boot-strap air evaporative cooling system, the evaporator is provided |
| A. | between the combustion chamber and the first heat exchanger |
| B. | between the first heat exchanger and the secondary compressor |
| C. | between the secondary compressor and the second heat exchanger |
| D. | between the second heat exchanger and the cooling turbine |
| Answer» E. | |
| 17. |
The atmospheric air at dry bulb temperature of 15°C enters a heating coil maintained at 40°C. The air leaves the heating coil at 25°C. The by-pass factor of the heating coil is |
| A. | 0.376 |
| B. | 0.4 |
| C. | 0.6 |
| D. | 0.67 |
| Answer» D. 0.67 | |
| 18. |
The logarithmic mean temperature difference (tm) is given by (where Δt1 and Δt2 are temperature differences between the hot and cold fluids at entrance and exit) |
| A. | tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) |
| B. | tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) |
| C. | tm = (Δt1 - Δt1) loge(Δt1/Δt1) |
| D. | tm = loge (Δt1 - Δt2)/ Δt1/Δt2 |
| Answer» B. tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) | |
| 19. |
The process, generally used in summer air conditioning to cool and dehumidify the air, is called |
| A. | humidification |
| B. | dehumidification |
| C. | heating and humidification |
| D. | cooling and dehumidification |
| Answer» E. | |
| 20. |
The sensible heat factor during the heating and humidification process is given by (where h1 = Enthalpy of air entering the heating coil, h2 = Enthalpy of air leaving the heating coil, and hA = Enthalpy of air at the end of humidification process) |
| A. | (hA - h2)/ (h1 - h2) |
| B. | (h2 - hA)/ (h1 - h2) |
| C. | (h1 - h2)/ (hA - h2) |
| D. | (hA - h1)/ (h2 - h1) |
| Answer» E. | |
| 21. |
The air cooling system mostly used in transport type aircrafts is |
| A. | simple air cooling system |
| B. | simple evaporative air cooling system |
| C. | boot-strap air cooling system |
| D. | all of these |
| Answer» D. all of these | |
| 22. |
In a black body, all radiations are rejected. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 23. |
The heat transfer by conduction through a thick cylinder(Q) is given by (where T1 = Higher temperature, T2 = Lower temperature, r1 = Inside radius, r2 = Outside radius, l = Length of cylinder, and k = Thermal conductivity) |
| A. | Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) |
| B. | Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] |
| C. | Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) |
| D. | Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) |
| Answer» B. Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] | |
| 24. |
The superheated vapour region, in a pressure enthalpy chart, is represented by the space |
| A. | to the left of saturated liquid line |
| B. | to the right of saturated liquid line |
| C. | between the saturated liquid line and saturated vapour line |
| D. | none of the above |
| Answer» D. none of the above | |
| 25. |
The curved lines on a psychrometric chart indicates |
| A. | dry bulb temperature |
| B. | wet bulb temperature |
| C. | dew point temperature |
| D. | relative humidity |
| Answer» E. | |
| 26. |
The emissive power of a body depends upon its |
| A. | temperature |
| B. | physical nature |
| C. | wave length |
| D. | all of these |
| Answer» E. | |
| 27. |
The ratio of emissive power of a body to the emissive power of a perfectly black body is called emissivity. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 28. |
The by-pass factor (B. P. F.) in case of sensible heating of air is (Where td1 = Dry bulb temperature of air entering the heating coil, td2 = Dry bulb temperature of air leaving the heating coil, and td3 = Dry bulb temperature of heating coil) |
| A. | (td₂ - td₃)/(td₃ - td₁) |
| B. | (td₃ - td₂)/(td₃ - td₁) |
| C. | (td₃ - td₁)/(td₂ - td₃) |
| D. | (td₃ - td₁)/(td₃ - td₂) |
| Answer» C. (td₃ - td₁)/(td₂ - td₃) | |
| 29. |
If the evaporator temperature is kept constant, the coefficient of performance of a refrigeration cycle __________ with the increase in condenser temperature. |
| A. | increases |
| B. | decreases |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 30. |
The dehumidification process, on the psychrometric chart, is shown by |
| A. | horizontal Sine |
| B. | vertical line |
| C. | inclined line |
| D. | curved line |
| Answer» C. inclined line | |
| 31. |
The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T1 = Lowest absolute temperature, and T2 = Highest absolute temperature) |
| A. | T₁ / (T₂ - T₁) |
| B. | (T₂ - T₁)/T₁ |
| C. | (T₁ - T₂)/T₁ |
| D. | T₂/ (T₂ - T₁) |
| Answer» B. (T₂ - T₁)/T₁ | |
| 32. |
Stefan-Boltzmann law is applicable for heat transfer by convection. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 33. |
The coefficient of performance of vapour compression refrigeration system is quite __________ as compared to air refrigeration system. |
| A. | low |
| B. | high |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 34. |
The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles caused by some mechanical means, is known as |
| A. | conduction |
| B. | free convection |
| C. | forced convection |
| D. | radiation |
| Answer» D. radiation | |
| 35. |
In order to collect liquid refrigerant and to prevent it from going to a __________ , a device known as accumulator is used at the suction of compressor. |
| A. | compressor |
| B. | condenser |
| C. | expansion valve |
| D. | evaporator |
| Answer» B. condenser | |
| 36. |
The coefficient of performance (C.O.P.) of a refrigerator working as a heat pump is given by |
| A. | (C.O.P.)P = (C.O.P.)R + 2 |
| B. | (C.O.P.)P = (C.O.P.)R + 1 |
| C. | (C.O.P)P = (C.O.P)R - 1 |
| D. | (C.O.P)P = (C.O.P)R |
| Answer» C. (C.O.P)P = (C.O.P)R - 1 | |
| 37. |
The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number)n, where n is equal to |
| A. | -1/3 |
| B. | -2/3 |
| C. | 1 |
| D. | -1 |
| Answer» B. -2/3 | |
| 38. |
A refrigerant with the highest critical pressure is |
| A. | R-11 |
| B. | R-12 |
| C. | R-22 |
| D. | Ammonia |
| Answer» E. | |
| 39. |
The most commonly used method for the design of duct size is the |
| A. | velocity reduction method |
| B. | equal friction method |
| C. | static regain method |
| D. | dual or double method |
| Answer» D. dual or double method | |
| 40. |
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» E. | |
| 41. |
Most thermostatic expansion valves are set for a superheat of |
| A. | 5°C |
| B. | 10°C |
| C. | 15°C |
| D. | 20°C |
| Answer» B. 10°C | |
| 42. |
Two long parallel surfaces each of emissivity 0.7 are maintained at different temperatures and accordingly have radiation heat exchange between them. It is desired to reduce 75% of the radiant heat transfer by inserting thin parallel shields of emissivity 1 on both sides. The number of shields should be |
| A. | one |
| B. | two |
| C. | three |
| D. | four |
| Answer» D. four | |
| 43. |
The capillary tube is not used in large capacity refrigeration systems because |
| A. | cost is too high |
| B. | capacity control is not possible |
| C. | it is made of copper |
| D. | required pressure drop can not be achieved |
| Answer» C. it is made of copper | |
| 44. |
In case of sensible heating of air, the coil efficiency is given by (where B.P.F. = By-pass factor) |
| A. | B.P.F. - 1 |
| B. | 1 - B.P.F. |
| C. | 1 + B.RF. |
| D. | None of these |
| Answer» C. 1 + B.RF. | |
| 45. |
The process of removing moisture from the air, without change in its dry bulb temperature, is called dehumidification. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 46. |
The leakage in a refrigeration system using freon is detected by |
| A. | halide torch |
| B. | sulphur sticks |
| C. | soap and water |
| D. | all of these |
| Answer» B. sulphur sticks | |
| 47. |
Oil separator in a refrigeration cycle is installed |
| A. | before compressor |
| B. | between compressor and condenser |
| C. | between condenser and evaporator |
| D. | between condenser and expansion valve |
| Answer» C. between condenser and evaporator | |
| 48. |
The freezing point of carbon dioxide is equal to boiling point of R-12. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 49. |
The process of adding moisture to the air, without change in its dry bulb temperature, is known as humidification. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 50. |
The temperature of air recorded by a thermometer, when it is not effected by the moisture present in the air, is called |
| A. | wet bulb temperature |
| B. | dry bulb temperature |
| C. | dew point temperature |
| D. | none of these |
| Answer» C. dew point temperature | |