MCQOPTIONS
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MCQOPTIONS
This section includes 265 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 251. |
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, is called |
| A. | humidity ratio |
| B. | relative humidity |
| C. | absolute humidity |
| D. | degree of saturation |
| Answer» E. | |
| 252. |
For unsaturated air, the dew point temperature is __________ wet bulb temperature. |
| A. | equal to |
| B. | less than |
| C. | more than |
| Answer» C. more than | |
| 253. |
Dehydration is the process of removing water vapour from the surrounding air. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 254. |
The cooling of air, without any change in its specific humidity, is known as sensible cooling. |
| A. | Correct |
| B. | Incorrect |
| Answer» B. Incorrect | |
| 255. |
The capacity of the cooling tower and spray ponds __________ as the wet bulb temperature of air decreases. |
| A. | increases |
| B. | decreases |
| Answer» B. decreases | |
| 256. |
A mixture of dry air and water vapour, when the air has diffused the maximum amount of water vapour into it, is called |
| A. | dry air |
| B. | moist air |
| C. | saturated air |
| D. | specific humidity |
| Answer» D. specific humidity | |
| 257. |
The value of the wave length for maximum emissive power is given by |
| A. | Kirchhoff's law |
| B. | Stefan's law |
| C. | Wein's law |
| D. | Planck's law |
| Answer» D. Planck's law | |
| 258. |
Emissivity of a body will be equal to its absorptivity at all temperatures. |
| A. | Yes |
| B. | No |
| Answer» C. | |
| 259. |
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 = 1 kJ/kg) |
| A. | 25 kJ/kg |
| B. | 50 kJ/kg |
| C. | l00 kJ/kg |
| D. | 125 kJ/kg |
| Answer» C. l00 kJ/kg | |
| 260. |
Wet bulb temperature indicates the moisture content in air. |
| A. | Agree |
| B. | Disagree |
| Answer» B. Disagree | |
| 261. |
A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100° C and leaves at 60° C. A cold fluid enters the heat exchanger at 40° C. The mean temperature difference between the two fluids is |
| A. | 20°C |
| B. | 40°C |
| C. | 60°C |
| D. | 66.7°C |
| Answer» B. 40°C | |
| 262. |
The inclined and non-uniformly spaced straight lines on a psychrometric chart indicates wet bulb temperature. |
| A. | Agree |
| B. | Disagree |
| Answer» B. Disagree | |
| 263. |
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. | |
| 264. |
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 | |
| 265. |
The expansion valve in a refrigerator controls the flow of refrigerant. |
| A. | Correct |
| B. | Incorrect |
| Answer» B. Incorrect | |