MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 482 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 251. |
_ The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of 'n' is exactly 4 for$? |
| A. | Black painted bodies only |
| B. | All bodies |
| C. | Polished bodies only |
| D. | A black body |
| Answer» C. Polished bodies only | |
| 252. |
_ A diathermaneous substance __________ the thermal radiation completely.$? |
| A. | Absorbs |
| B. | Reflects |
| C. | Transmits |
| D. | None of these |
| Answer» D. None of these | |
| 253. |
_ The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoffs law.$? |
| A. | Wavelength of radiation |
| B. | Nature of the body |
| C. | Temperature of the body |
| D. | None of these |
| Answer» D. None of these | |
| 254. |
_ Trap is used to remove __________ from steam pipe lines.$? |
| A. | Steam |
| B. | Condensate |
| C. | Non-condensables |
| D. | None of these |
| Answer» C. Non-condensables | |
| 255. |
_ In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass __________ through the heat exchanger.$? |
| A. | Once |
| B. | Twice |
| C. | Thrice |
| D. | Four times |
| Answer» C. Thrice | |
| 256. |
_ In forced convection, the heat transfer depends on$? |
| A. | Re, Pr |
| B. | Re, Gr |
| C. | Mainly Gr |
| D. | Re only |
| Answer» B. Re, Gr | |
| 257. |
_ A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m².K. The Biot number is$? |
| A. | 5.6 |
| B. | 0.025 |
| C. | 3.5 |
| D. | 0.0035 |
| Answer» C. 3.5 | |
| 258. |
_ In a multipass shell and tube heat exchanger, tube side return pressure loss is equal to __________ the velocity head.$? |
| A. | Twice |
| B. | Four times |
| C. | Square root of |
| D. | Square of |
| Answer» C. Square root of | |
| 259. |
_ In counter flow compared to parallel flow,$? |
| A. | LMTD is greater |
| B. | Less surface area is required for a given heat transfer rate |
| C. | Both A and B |
| D. | More surface area is required for a given heat transfer rate |
| Answer» D. More surface area is required for a given heat transfer rate | |
| 260. |
_ As per Kirchoffs law, the ratio of the total radiating power to the absorptivity of a body depends on the$? |
| A. | Temperature of the body only |
| B. | Wavelength of monochromatic radiation |
| C. | Both A and B |
| D. | Nature of material of body |
| Answer» B. Wavelength of monochromatic radiation | |
| 261. |
_ Kirchoff's law is applicable to$? |
| A. | Monochromatic radiation only |
| B. | Total radiation only |
| C. | Both A and B |
| D. | Only volumes and not to surfaces |
| Answer» D. Only volumes and not to surfaces | |
| 262. |
_ Heat transfer by natural convection is enhanced in system with$? |
| A. | High viscosity |
| B. | High co-efficient of thermal expansion |
| C. | Low temperature gradients |
| D. | Low density change with temperature |
| Answer» C. Low temperature gradients | |
| 263. |
_ Steam traps are provided in steam carrying pipelines to$? |
| A. | Condense steam |
| B. | Release excess steam pressure by bleeding steam |
| C. | Remove condensate and inert gases |
| D. | None of these |
| Answer» D. None of these | |
| 264. |
_ Radiant energy received by a body is proportional to (where, d = the distance between the object emitting radiation and that receiving it.)$? |
| A. | ‚à öd |
| B. | d |
| C. | d2 |
| D. | d1.5 |
| Answer» D. d1.5 | |
| 265. |
_ In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid$? |
| A. | Is inversely proportional to the resistance across which the drop occurs |
| B. | And the wall are proportional to individual resistances |
| C. | And the wall is not related |
| D. | None of these |
| Answer» C. And the wall is not related | |
| 266. |
_ The type of liquor circulation system to be ' employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid.$? |
| A. | Viscosity |
| B. | Density |
| C. | Thermal conductivity |
| D. | Corrosive nature |
| Answer» B. Density | |
| 267. |
_ Loss of heat from untagged steam pipe to the ambient air is by$? |
| A. | Conduction |
| B. | Convection |
| C. | Radiation |
| D. | All of the above |
| Answer» E. | |
| 268. |
_ Baffles in the shell side of a shell and tube heat exchanger$? |
| A. | Increase the cross-section of the shell side liquid |
| B. | Force the liquid to flow parallel to the bank |
| C. | Increase the shell side heat transfer co-efficient |
| D. | Decrease the shell side heat transfer co-efficient |
| Answer» D. Decrease the shell side heat transfer co-efficient | |
| 269. |
_ With increase in temperature, the thermal conductivity of non-metallic amorphous solids$? |
| A. | Decreases |
| B. | Increases |
| C. | Remains constant |
| D. | First decreases upto certain temperature and then increases |
| Answer» C. Remains constant | |
| 270. |
__The statement that "maximum wavelength of radiation is inversly proportional to the temperature" is __________ law.__ |
| A. | Stefan-Boltzman's |
| B. | Planck's |
| C. | Wien's displacement |
| D. | None of these |
| Answer» D. None of these | |
| 271. |
__Harmonic mean temperature difference is given by__ |
| A. | ‚à ö(ŒîT‚ÇÅ . ŒîT‚ÇÇ) |
| B. | 2.(ΔT₁ . ΔT₂)/(ΔT₁ + ΔT₂) |
| C. | 2.(ΔT₁ . ΔT₂)(ΔT₁ - ΔT₂) |
| D. | (ΔT₁ - ΔT₂)/(ΔT₁ . ΔT₂) |
| Answer» C. 2.(≈í√ÆT‚Äö√á√Ö . ≈í√ÆT‚Äö√á√á)(≈í√ÆT‚Äö√á√Ö - ≈í√ÆT‚Äö√á√á) | |
| 272. |
__Which of the following is directly concerned with the heat transfer?__ |
| A. | Strouhal number |
| B. | Sherwood number |
| C. | Euler number |
| D. | Grashoff number |
| Answer» E. | |
| 273. |
__Steam consumption in kg/hr in case of an evaporator is given by (where, C & E are capacity the economy of the evaporator respectively)__ |
| A. | C/E |
| B. | E/C |
| C. | CE |
| D. | 1/CE |
| Answer» B. E/C | |
| 274. |
__Hot water (0.01 m³ /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m³/min) of density 800 kg/m³ and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately__ |
| A. | 32 |
| B. | 37 |
| C. | 45 |
| D. | 50 |
| Answer» B. 37 | |
| 275. |
__For an ideal black body__ |
| A. | Absorptivity = 1 |
| B. | Reflectivity = 1 |
| C. | Emissivity = 0 |
| D. | Transmissivity = 1 |
| Answer» B. Reflectivity = 1 | |
| 276. |
__Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator?__ |
| A. | Long vertical evaporator |
| B. | Horizontal tube evaporator |
| C. | Agitated film evaporator |
| D. | Calenderia vertical tube evaporator |
| Answer» D. Calenderia vertical tube evaporator | |
| 277. |
__In pipe flow, heat is transferred from hot wall to the liquid by__ |
| A. | Conduction only |
| B. | Forced convection only |
| C. | Forced convection and conduction |
| D. | Free and forced convection |
| Answer» D. Free and forced convection | |
| 278. |
__The interchange factor for radiation heat transfer from surface 'x' to surface 'y' in case of an infinite parallel planes with emis-sivities εx & εy is given by__ |
| A. | Εx + εy |
| B. | Εx . εy |
| C. | 1/εx + 1/εy |
| D. | (εx + εy)/(εx + εy - εx . εy) |
| Answer» E. | |
| 279. |
__Rate of crystallisation does not depend upon the__ |
| A. | Extent of supersaturation |
| B. | Turbulence within the solution |
| C. | Number and active surface area of the crystals |
| D. | None of these |
| Answer» E. | |
| 280. |
__A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ?__ |
| A. | Cube |
| B. | Plate |
| C. | Sphere |
| D. | All of the above |
| Answer» D. All of the above | |
| 281. |
__Solid angle subtended by the finite surface at the radiating element is__ |
| A. | Called the view factor |
| B. | Called the angle of vision |
| C. | Proportional to the square of the distance between surfaces |
| D. | Expressed in terms of radians |
| Answer» C. Proportional to the square of the distance between surfaces | |
| 282. |
__Heat produced when a steady state current, I passes through an electrical conductor having resistance, 'R' is__ |
| A. | IR |
| B. | I²R |
| C. | IR² |
| D. | I²R² |
| Answer» C. IR¬¨‚⧠| |
| 283. |
__Film boiling is usually not desired in commercial equipments, because__ |
| A. | The heat transfer rate is low in view of the large temperature drop |
| B. | It is difficult to maintain |
| C. | It is not economic |
| D. | None of these |
| Answer» B. It is difficult to maintain | |
| 284. |
__With increase in porosity, the thermal conductivity of a solid substance__ |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | May increase or decrease; depends on the solid |
| Answer» C. Remains unchanged | |
| 285. |
__The range of electromagnetic spectrum important in heat transfer by radiation is __________ microns.__ |
| A. | 0.38-0.78 |
| B. | 0.5-50 |
| C. | 100-1000 |
| D. | 5-50 |
| Answer» C. 100-1000 | |
| 286. |
__(Cp . μ)/K is termed as the __________ number.__ |
| A. | Grashoff |
| B. | Nusselt |
| C. | Prandtl |
| D. | Stanton |
| Answer» D. Stanton | |
| 287. |
__In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used__ |
| A. | In low range of temperature differences |
| B. | In high range of temperature differences |
| C. | Because of its low cost |
| D. | To prevent corrosion of the tube bundles |
| Answer» C. Because of its low cost | |
| 288. |
__Which characteristic of a fluid is not important in deciding its route in a shell and tube heat exchanger?__ |
| A. | Corrosiveness |
| B. | Fouling characteristic |
| C. | Viscosity |
| D. | None of these |
| Answer» E. | |
| 289. |
_Nusselt number is the ratio of the$? |
| A. | Temperature gradient of the wall to that across the entire pipe |
| B. | Temperature difference to the temperature gradient at the wall |
| C. | Heat flux at the wall to that across the entire pipe |
| D. | None of these |
| Answer» D. None of these | |
| 290. |
_In case of evaporators, liquid entrainment results primarily due to$? |
| A. | High vacuum in the evaporator |
| B. | High evaporation rate |
| C. | Foaming of the solution |
| D. | High heat transfer rate |
| Answer» D. High heat transfer rate | |
| 291. |
_A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of materialA is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C.$? |
| A. | 6 |
| B. | 12 |
| C. | 18 |
| D. | 24 |
| Answer» C. 18 | |
| 292. |
_In a shell and tube heat exchanger, the tube side heat transfer co-efficient just at the entrance of the tube is$? |
| A. | Infinity |
| B. | Zero |
| C. | Same as average heat transfer co-efficient for tube side |
| D. | None of these |
| Answer» B. Zero | |
| 293. |
_In a shell and tube heat exchanger, floating head is used for$? |
| A. | Large temperature differentials |
| B. | High heat transfer co-efficient |
| C. | Low pressure drop |
| D. | Less corrosion of tubes |
| Answer» B. High heat transfer co-efficient | |
| 294. |
_Air is best heated with steam in a heat exchanger of$? |
| A. | Plate type |
| B. | Double pipe type with fin on steam side |
| C. | Double pipe type with fin on air side |
| D. | Shell and tube type |
| Answer» D. Shell and tube type | |
| 295. |
_Radiation energy is emitted by all the substances, which are above$? |
| A. | 0°K |
| B. | 0°C |
| C. | 100°C |
| D. | Room temperature |
| Answer» B. 0¬¨‚àûC | |
| 296. |
_The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation.$? |
| A. | Greater than |
| B. | Lower than |
| C. | Is same as |
| D. | Half |
| Answer» C. Is same as | |
| 297. |
_In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid$? |
| A. | Varies directly as the area and the LMTD |
| B. | Directly proportional to LMTD and inversely proportional to the area |
| C. | Varies as square of the area |
| D. | None of these |
| Answer» B. Directly proportional to LMTD and inversely proportional to the area | |
| 298. |
_With increase in temperature, the thermal conductivity of steel$? |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | Increases exponentially |
| Answer» C. Remains unchanged | |
| 299. |
_Which has the lowest Prandtl number?$? |
| A. | Liquid metal |
| B. | Aqueous solution |
| C. | Water |
| D. | Lube oil |
| Answer» B. Aqueous solution | |
| 300. |
_In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient$? |
| A. | Increases |
| B. | Decreases |
| C. | Is not affected |
| D. | May increase or decrease; depends on the feed |
| Answer» C. Is not affected | |