MCQOPTIONS
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MCQOPTIONS
This section includes 253 Mcqs, each offering curated multiple-choice questions to sharpen your Heat Transfer (HT) knowledge and support exam preparation. Choose a topic below to get started.
| 201. |
Which is the unit of Stefan Boltzmann constant |
| A. | W/m2 K4 |
| B. | erg/cm2-sec-K4 |
| C. | cal/cm2-sec K4 |
| D. | kcal/m2-hr-K4 |
| E. | All of the above |
| Answer» F. | |
| 202. |
A thin circulr disc has a concentric hole in it. On heating the diameter of hole will |
| A. | decrease |
| B. | remain constant |
| C. | 37,500 kg |
| D. | increase |
| Answer» E. | |
| 203. |
The unit of thermal conductivity in M.K.S. unit is |
| A. | kcal/m/?C |
| B. | kcal/m/sec?C |
| C. | kcal/m2/?C sec |
| D. | None of the above |
| E. | Nichrome |
| Answer» D. None of the above | |
| 204. |
The unit of thermal conductivity in S.I. units is |
| A. | KJ/m-hr-?K |
| B. | KJ/m-hr?C |
| C. | W/m?K |
| D. | W/m-hr?C |
| E. | W/m-hr-?K |
| Answer» D. W/m-hr?C | |
| 205. |
The process of heat transfer during the re-entry of satellites and missiles, at very high speeds, into the earth's atmosphere is known as |
| A. | Radiation |
| B. | Viscous dissipation |
| C. | Triple flow |
| D. | Ablation |
| E. | None of the above |
| Answer» E. None of the above | |
| 206. |
In which of the following will the evaporation rate be large? |
| A. | Leaking water from pipe. |
| B. | Near the mountain |
| C. | Covered swimming pool |
| D. | Narrow river surrounded by trees |
| E. | Salt pan near the sea |
| Answer» C. Covered swimming pool | |
| 207. |
Which one of the following materials will have highest value of thermal conductivity? |
| A. | Copper |
| B. | Lead |
| C. | Brass |
| D. | Aluminium |
| E. | Steel |
| Answer» B. Lead | |
| 208. |
A body which transmits all the radiations falling on it is known as |
| A. | Black body |
| B. | Grey body |
| C. | Transparent body |
| D. | White body |
| E. | None of the above |
| Answer» D. White body | |
| 209. |
Heat is transferred by conduction, convection and radiation in |
| A. | Melting of ice |
| B. | Refrigerator freezer coils |
| C. | Boiler furnaces |
| D. | Condensation of steam in a condenser |
| E. | Insulated pipes carrying hot water |
| Answer» D. Condensation of steam in a condenser | |
| 210. |
Which liquid metal is supposed to be the best conductor |
| A. | Zinc |
| B. | Lead |
| C. | Potassium |
| D. | Mercury |
| E. | Sodium |
| Answer» F. | |
| 211. |
In sugar mills cane juice is evaporated in |
| A. | Long vertical tube evaporators |
| B. | Flash evaporator |
| C. | Horizontal tube evaporators |
| D. | Zig-zag tube evaporator |
| E. | Short vertical tube evaporators |
| Answer» B. Flash evaporator | |
| 212. |
Thermal conductivity of water at 20?C is nearly |
| A. | 0.051 |
| B. | 1 |
| C. | 0.11 |
| D. | 0.09 |
| E. | 0.5 |
| Answer» F. | |
| 213. |
The diathermous body is one that |
| A. | diffuses all the thermal rays in the different directions |
| B. | allows all the incident radiation to pass through it |
| C. | 37,500 kg |
| D. | negligible absorptivity but high reflectivity |
| E. | absorbs all the thermal rays |
| Answer» C. 37,500 kg | |
| 214. |
The material preferred for the fabrication of fruit juice concentrator is |
| A. | Mild steel sheet |
| B. | Brass |
| C. | Cast iron |
| D. | Stainless steel sheet |
| E. | Copper |
| Answer» E. Copper | |
| 215. |
The value of reheat factor is of the order of |
| A. | 37,500 kg |
| B. | Less than 1 |
| C. | 1.02 to 1.06 |
| D. | 1.2 to 1.6 |
| E. | More than 2 |
| Answer» D. 1.2 to 1.6 | |
| 216. |
The temperature reading taken using Centigrade and Fahrenheit thermometers are plotted on a graph -?C along X-axis, ?F along Y-axis. The shape of graph would be |
| A. | Straight line cutting an intercept on the negative Y-axis |
| B. | Straight line cutting an intercept on the positive Y-axis |
| C. | Straight line cutting an intercept on the negative X-axis |
| D. | 273?C |
| E. | Straight line cutting an intercept on the positive X-axis |
| Answer» F. | |
| 217. |
Dropwise condensation occurs on a |
| A. | Glazed surface |
| B. | Smooth surface |
| C. | Oily surface |
| D. | Coated surface |
| E. | None of the above |
| Answer» D. Coated surface | |
| 218. |
Unsteady state of heat flow occurs in |
| A. | Flow of heat through furnace walls |
| B. | Flow of heat through insulated pipe with constant surface temperature |
| C. | Annealing of castings |
| D. | Flow of heat through refrigerator walls |
| E. | None of the above |
| Answer» D. Flow of heat through refrigerator walls | |
| 219. |
A slab of ice has one-half covered with black cloth and the other half with white cloth. The slab is now placed in sunlight. It will be observed that |
| A. | 37,500 kg |
| B. | more ice will melt under black cloth |
| C. | more ice will melt under white cloth |
| D. | ice will not melt |
| E. | equal amount of ice will melt under the two cloths |
| Answer» C. more ice will melt under white cloth | |
| 220. |
The value of Prandtl number for air is of the order of |
| A. | 67 |
| B. | 1000 |
| C. | 0.7 |
| D. | 9.7 |
| E. | 0.065 |
| Answer» D. 9.7 | |
| 221. |
In the temperature of air above a pond is 8?C thermal conductivity of ice is 0.005 C.G.S. units, latent heat of fusion of ice is 79.9 cal/gram the density of ice is 1 gm/cu.m, the time taken for the formation of ice layer of 1 cm thickness is |
| A. | 200 seconds |
| B. | 100 seconds |
| C. | 12.5 seconds |
| D. | 10 seconds |
| E. | None of the above |
| Answer» D. 10 seconds | |
| 222. |
Agitated film evaporator is suitable for concentrating |
| A. | Insulating liquids |
| B. | Low temperature liquids |
| C. | Viscous liquids |
| D. | Corrosive liquids |
| E. | Liquid metal |
| Answer» D. Corrosive liquids | |
| 223. |
Which is not the assumption in Fourier's equation of heat conduction? |
| A. | Uniform area of cross-section |
| B. | Steady heat flow |
| C. | Homogeneous substance |
| D. | Constant temperature difference |
| E. | Thermal conductivity independent of temperature |
| Answer» B. Steady heat flow | |
| 224. |
The numerical value of which property of air generally drops with rising temperature |
| A. | Thermal diffusivity |
| B. | Density |
| C. | Kinematic viscosity |
| D. | Thermal conductivity |
| E. | Dynamic viscosity |
| Answer» C. Kinematic viscosity | |
| 225. |
Prandtl number for liquid metals is generally in the range |
| A. | 1000 to 10,000 |
| B. | 0.003 to 0.01 |
| C. | 10 to 100 |
| D. | 100 to 1000 |
| E. | 37,500 kg |
| Answer» C. 10 to 100 | |
| 226. |
Least value of Prandlt number can be expected in case of |
| A. | Salt solution |
| B. | Water |
| C. | Sugar solution |
| D. | Petroleum products |
| E. | Liquid metals |
| Answer» F. | |
| 227. |
The process of removal of oil from oil cakes is known as |
| A. | Leaching |
| B. | Decoction |
| C. | Osmosis |
| D. | Soret effect |
| E. | None of the above |
| Answer» B. Decoction | |
| 228. |
For temperature below -40?C which one of the following substance can be used as thermometric substance |
| A. | Alcohol |
| B. | Pentane |
| C. | Ether |
| D. | Any of the above |
| E. | None of the above |
| Answer» E. None of the above | |
| 229. |
If in a system ratios of the velocity and acceleration of the homologous particles are equal, the similarity being considered is |
| A. | geometric similarity |
| B. | kinematic similarity |
| C. | dynamic similarity |
| D. | thermal similarity |
| E. | 37,500 kg |
| Answer» C. dynamic similarity | |
| 230. |
In the electrical network analysis method the total radiation which leaves a surface per unit time per unit area is termed as |
| A. | Flux |
| B. | Potential |
| C. | Irradiation |
| D. | Spatial resistance |
| E. | Radiosity |
| Answer» F. | |
| 231. |
A block of wood and a block of metal feel equally cold or equally hot when touched. Then their common temperature is |
| A. | 0?K |
| B. | 0?F |
| C. | 0?C |
| D. | 37,500 kg |
| E. | the same as that of the human body |
| Answer» F. | |
| 232. |
A black body absorbs all radiations. As a result of absorption of these radiations |
| A. | A black body shines |
| B. | The temperature of black body rises |
| C. | Black body radiates energy to other bodies |
| D. | Black body becomes good conductor of heat |
| E. | None of the above |
| Answer» C. Black body radiates energy to other bodies | |
| 233. |
If the absorptivity plus reflectivity of a body equals 1, then the body is known as |
| A. | Black body |
| B. | Grey body |
| C. | Opaque body |
| D. | White body |
| E. | None of the above |
| Answer» D. White body | |
| 234. |
The triple point temperature for water is |
| A. | 0?K |
| B. | 0.1?C |
| C. | 0.01?C |
| D. | 0?C |
| E. | 0.001?C |
| Answer» D. 0?C | |
| 235. |
Which of the following material has highest value of thermal diffusivity? |
| A. | Steel |
| B. | Concrete |
| C. | Lead |
| D. | Mineral wool |
| E. | Wood |
| Answer» D. Mineral wool | |
| 236. |
The conditions under which three phases of matter can coexist in equilibrium, is known as |
| A. | Common point |
| B. | Triple point |
| C. | Absolute point |
| D. | Basic point |
| E. | Standard point |
| Answer» C. Absolute point | |
| 237. |
A sphere of radius 40 cm is lagged to a radius of 50 cm. The temperatures of outer and inner surfaces are 66?C and 235?C respectively. Thermal conductivity of logging per cm thickness is 0.7 kcal/m-hr?C. The rate of heat leakage will be |
| A. | 500 kcal/hr |
| B. | 1.49 kcal/hr |
| C. | 666 kcal/hr |
| D. | 298 kcal/hr |
| E. | 398 kcal/hr |
| Answer» E. 398 kcal/hr | |
| 238. |
The quantity of heat required to change the temperature of 1 gm of ice from -6?C to -5?C is known as |
| A. | Freezing heat |
| B. | Cold heat |
| C. | Latent heat of freezing |
| D. | Specific heat |
| E. | Heat of vaporization |
| Answer» E. Heat of vaporization | |
| 239. |
A wet solid is to be dried from 80% to 50% moisture (on wet basis). Calculate the moisture to be evaporated for 10 tonns of dried product? |
| A. | 3750 kg |
| B. | 37,500 kg |
| C. | 375 kg |
| D. | 7500 kg |
| E. | 13,750 kg |
| Answer» C. 375 kg | |
| 240. |
Grashoff number has significant role in heat transfer by |
| A. | 37,500 kg |
| B. | radiation |
| C. | natural connection |
| D. | conduction |
| E. | Forced convection |
| Answer» D. conduction | |
| 241. |
When a vapour condenses into a liquid |
| A. | It absorbs heat |
| B. | It evolves heat |
| C. | Its temperature rises |
| D. | Its temperature drops |
| E. | None of the above |
| Answer» C. Its temperature rises | |
| 242. |
The expression (A2-A1)/loge (A2/A1) for a hollow cylinder is known as |
| A. | Logarithmic mean radius |
| B. | Mean area of heat transfer |
| C. | The rate of heat transfer |
| D. | None of the above |
| E. | Nichrome |
| Answer» C. The rate of heat transfer | |
| 243. |
"The boiling point of a solution is a linear function of water at the same pressure". The above statement is associated with |
| A. | Dubring's rule |
| B. | Petit and Dulong law |
| C. | Fick's rule |
| D. | Reynolds law |
| E. | None of the above |
| Answer» B. Petit and Dulong law | |
| 244. |
Which of the following has higher thermal conductivity as compared to the remaining? |
| A. | Air |
| B. | Water |
| C. | 37,500 kg |
| D. | Hydrogen |
| E. | Oxygen |
| Answer» C. 37,500 kg | |
| 245. |
Heat conduction does not occur |
| A. | If the parts of a body are not in motion relative to one another |
| B. | If the bodies are immersed in water |
| C. | If the temperature difference between the bodies does not exist |
| D. | If a physical body is impermeable to any kind of rays |
| E. | If the bodies are kept in vacuum |
| Answer» D. If a physical body is impermeable to any kind of rays | |
| 246. |
For all substances the absorptivity must lie between |
| A. | 0 and + 0.5 |
| B. | ?1 and +1 |
| C. | ?0.5 and + 0.5 |
| D. | 0 and 0.1 |
| E. | 0 and 1 |
| Answer» F. | |
| 247. |
Thermal diffusivity is least for |
| A. | Mercury |
| B. | Rubber |
| C. | Lead |
| D. | Iron |
| E. | Aluminium |
| Answer» C. Lead | |
| 248. |
A dimensionless number which is the ratio of mass heat flow rate to the heat flow rate by conduction under a unit temperature gradient and through a thickness L is known as |
| A. | Nusselt number |
| B. | Prandtl number |
| C. | Weber number |
| D. | Grashof number |
| E. | Peclet number |
| Answer» F. | |
| 249. |
If the roof of a house is painted with a shiny metallic paint, the temperature inside will |
| A. | Rise |
| B. | Fall |
| C. | Remain unchanged |
| D. | Depends on other factors |
| E. | None of the above |
| Answer» C. Remain unchanged | |
| 250. |
Hydrogen cannot be liquefied at room temperature because |
| A. | it is a diatomic gas |
| B. | its critical temperature is less than the room temperature |
| C. | 37,500 kg |
| D. | it has low density |
| E. | it has high specific heat |
| Answer» C. 37,500 kg | |