MCQOPTIONS
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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.
| 301. |
_Nusselt number for full developed, laminar, constant property flow in a pipe at uniform heat flux is$? |
| A. | 0.72 |
| B. | 4.364 |
| C. | 18 |
| D. | 83 |
| Answer» C. 18 | |
| 302. |
___________ chart is known as transient heat conduction chart.$? |
| A. | Dirhing's |
| B. | Heisler's |
| C. | Mollier's |
| D. | Cox |
| Answer» B. Heisler's | |
| 303. |
_An insulator should have$? |
| A. | Low thermal conductivity |
| B. | High thermal conductivity |
| C. | Less resistance to heat flow |
| D. | A porous structure |
| Answer» B. High thermal conductivity | |
| 304. |
_The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)$? |
| A. | αT |
| B. | α 1/T |
| C. | α T⁴ |
| D. | Independent of T |
| Answer» C. ≈í¬± T‚Äö√Ö¬• | |
| 305. |
_Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the$? |
| A. | Existence of thermal boundary layer |
| B. | Temperature gradient produced due to density difference |
| C. | Buoyancy of the bubbles produced at active nucleation site |
| D. | None of these |
| Answer» E. | |
| 306. |
_Heat transfer efficiency leading of energy conservation in a heat exchanger can be achieved by$? |
| A. | Keeping the heat transfer surface clean |
| B. | Enhancing the fluid pumping rate |
| C. | Increasing the tube length |
| D. | None of these |
| Answer» B. Enhancing the fluid pumping rate | |
| 307. |
_Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be$? |
| A. | 0.35 |
| B. | 0.45 |
| C. | 0.55 |
| D. | 0.85 |
| Answer» C. 0.55 | |
| 308. |
_In a shell and tube heat exchanger,$? |
| A. | The temperature drops in the two fluids and the wall are proportional to individual resistances |
| B. | The temperature drop is inversely proportional to the resistance across which the drop occurs |
| C. | There is no relationship between temperature drop and resistance |
| D. | The relationship is not generalised |
| Answer» B. The temperature drop is inversely proportional to the resistance across which the drop occurs | |
| 309. |
_An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a$? |
| A. | Boiler |
| B. | Heat exchanger |
| C. | Recuperator |
| D. | Regenerator |
| Answer» C. Recuperator | |
| 310. |
_1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is$? |
| A. | 520 |
| B. | 200 |
| C. | 400 |
| D. | 500 |
| Answer» D. 500 | |
| 311. |
_Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is$? |
| A. | 0.2 |
| B. | 0.4 |
| C. | 0.6 |
| D. | 0.8 |
| Answer» D. 0.8 | |
| 312. |
_Nusselt number (for forced convection heat transfer) is a function of the __________ number.$? |
| A. | Prandtl |
| B. | Reynolds |
| C. | Both A & B |
| D. | Neither A nor B |
| Answer» D. Neither A nor B | |
| 313. |
_For evaporation of viscous solution in a multiple effect evaporator, the prefered feeding scheme is$? |
| A. | Forward |
| B. | Backward |
| C. | Parallel |
| D. | None of these |
| Answer» C. Parallel | |
| 314. |
_Dietus-Boelter equation used for the determination of heat transfer co-efficient is valid$? |
| A. | For fluids in laminar flow |
| B. | For fluids in tubulent flow |
| C. | When Grashhoff number is very important |
| D. | For liquid metals |
| Answer» C. When Grashhoff number is very important | |
| 315. |
_Which of the following is generally considered as opaque surface towards radiations?$? |
| A. | Gases |
| B. | Solids |
| C. | Liquids |
| D. | Both B and C |
| Answer» E. | |
| 316. |
_(NRe.NPr)(D/L) is called the __________ number$? |
| A. | Peclet |
| B. | Stanton |
| C. | Graetz |
| D. | None of these |
| Answer» D. None of these | |
| 317. |
_What is the emissivity of a black body?$? |
| A. | 1 |
| B. | 0 |
| C. | 0.90 |
| D. | 0.5 |
| Answer» B. 0 | |
| 318. |
_The average heat transfer co-efficient over the entire length of the plate (ha) and the local heat transfer co-efficient (hL), in case of heat transfer over a flat plate in lminar zone is related as$? |
| A. | Ha = 0.8hL |
| B. | Ha = 2hL |
| C. | Ha = hL |
| D. | Ha= 5hL |
| Answer» C. Ha = hL | |
| 319. |
_Conductance is given by(where, x = thickness, A = heat flow area, K = thermal conductivity.)$? |
| A. | X/KA |
| B. | KA/x |
| C. | K/Ax |
| D. | A/Kx |
| Answer» C. K/Ax | |
| 320. |
_Fruit juice (a heat sensitive material) can be concentrated in a __________ evaporator.$? |
| A. | Long tube |
| B. | Falling film |
| C. | High pressure |
| D. | None of these |
| Answer» C. High pressure | |
| 321. |
_A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions ? Assume that the conductive heat transfer co-efficient is infinitely large.$? |
| A. | 5 minutes |
| B. | 10 minutes |
| C. | 20 minutes |
| D. | 40 minutes |
| Answer» B. 10 minutes | |
| 322. |
_In a shell and tube heat exchanger, the height of 25 percent cut baffles is equal to (where, D = inside diameter of shell)$? |
| A. | 0.25 D |
| B. | 0.75 D |
| C. | 0.50 D |
| D. | None of these |
| Answer» C. 0.50 D | |
| 323. |
_h.D/K is called the __________ number.$? |
| A. | Nusselt |
| B. | Peclet |
| C. | Rayleigh |
| D. | Grashoff |
| Answer» B. Peclet | |
| 324. |
_The rate of emission of radiation by a body does not depend upon the$? |
| A. | Wavelength of radiation |
| B. | Surface temperature of the body |
| C. | Nature of the surface |
| D. | Shape and porosity of the body |
| Answer» E. | |
| 325. |
_Stefan-Boltzman law which describes the radiation heat transfer states that, it is proportional to (where, t = temperature in °C T = absolute temperature in ° K )$? |
| A. | t‚Å¥ |
| B. | T‚Å¥ |
| C. | 1/t‚Å¥ |
| D. | 1/T‚Å¥ |
| Answer» C. 1/t‚Äö√Ö¬• | |
| 326. |
_Tube expansion allowances exist in __________ heat exchanger.$? |
| A. | Multipass fixed tube sheet |
| B. | U-tube |
| C. | Single pass fixed tube sheet |
| D. | None of these |
| Answer» C. Single pass fixed tube sheet | |
| 327. |
_Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re0.8 . Prn, is not valid, if the value of$? |
| A. | N = 0.4 is used for heating |
| B. | N = 0.3 is used for cooling |
| C. | Reynolds number for the flow involved is > 10000 |
| D. | Reynolds number for the flow involved is < 2100 |
| Answer» E. | |
| 328. |
_At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the$? |
| A. | Buffer zone |
| B. | Turbulent core |
| C. | Both A and B |
| D. | Viscous sub-layer |
| Answer» E. | |
| 329. |
_Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because$? |
| A. | Convection becomes important |
| B. | Conduction becomes important |
| C. | Radiation becomes important |
| D. | Sub-cooled boiling occurs |
| Answer» D. Sub-cooled boiling occurs | |
| 330. |
_The left face of a one dimensional slab of thickness 0.2 m is maintained at 80°C and the right face is exposed to air at 30°C. The thermal conductivity of the slab is 1.2 W/m.K and the heat transfer co-efficient from the right face is 10 W/m².K. At steady state, the temperature of the right face in °C is$? |
| A. | 77.2 |
| B. | 71.2 |
| C. | 63.8 |
| D. | 48.7 |
| Answer» E. | |
| 331. |
_Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids?$? |
| A. | Dittus-Boeltier equation |
| B. | Sieder-Tate equation |
| C. | Nusselt equation |
| D. | None of these |
| Answer» C. Nusselt equation | |
| 332. |
_Water always boils when its$? |
| A. | Temperature reaches 100° C |
| B. | Vapour pressure equals 76 cm of Hg |
| C. | Saturated vapour pressure equals the external pressure on its surface |
| D. | Saturated vapour pressure is less than the atmospheric pressure |
| Answer» D. Saturated vapour pressure is less than the atmospheric pressure | |
| 333. |
_Economy of an evaporator is influenced by the$? |
| A. | Steam pressure |
| B. | Feed temperature |
| C. | Number of effect |
| D. | Both B & C |
| Answer» E. | |
| 334. |
_A concentric double pipe heat exchanger as compared to the shell and tube heat exchanger for the same heat load requires$? |
| A. | Less heating surface |
| B. | More space |
| C. | Lower maintenance cost |
| D. | None of these |
| Answer» C. Lower maintenance cost | |
| 335. |
___________ heat exchanger is used for chilling oil to be dewaxed.$? |
| A. | U-tube |
| B. | Double pipe |
| C. | Fixed tube |
| D. | Floating head |
| Answer» C. Fixed tube | |
| 336. |
_Duhring rule is important in solving problems on$? |
| A. | Distillation |
| B. | Crystallisation |
| C. | Evaporation |
| D. | Humidification |
| Answer» D. Humidification | |
| 337. |
_Peclet number (Pe) is given by$? |
| A. | Pe = Re.Pr |
| B. | Pe = Re/Pr |
| C. | Pe = Pr/Re |
| D. | Pe = Nu.Re |
| Answer» B. Pe = Re/Pr | |
| 338. |
_Dropwise condensation occurs on __________ surfaces.$? |
| A. | Clean and dirt free |
| B. | Smooth clean |
| C. | Contaminated cooling |
| D. | Polished |
| Answer» D. Polished | |
| 339. |
_In case of a vertical tube evaporator, with increase in the liquor level, the$? |
| A. | Capacity of the evaporator is decreased |
| B. | Capacity of the evaporator is increased |
| C. | True temperature drop increases |
| D. | Both B and C |
| Answer» B. Capacity of the evaporator is increased | |
| 340. |
_A multiple effect evaporator as compared to a single effect evaporator of the same capacity has$? |
| A. | Lower heat transfer area |
| B. | Lower steam economy |
| C. | Higher steam economy |
| D. | Higher solute concentration in the product |
| Answer» D. Higher solute concentration in the product | |
| 341. |
_Analogy between mass and heat transfer is not applicable in case of$? |
| A. | Same velocity profile or equal eddy diffusivities |
| B. | Thermal or pressure mass diffusion |
| C. | Viscous heating or chemical reaction |
| D. | Both B and C |
| Answer» E. | |
| 342. |
_Water is normally used as a coolant in the heat exchange equipments mainly because ofits$? |
| A. | Abundance & high heat capacity |
| B. | Low density |
| C. | Low viscosity |
| D. | High fluidity |
| Answer» B. Low density | |
| 343. |
_Black liquor generated during paper manufacture is concentrated in a$? |
| A. | Single effect evaporator |
| B. | Single effect evaporator followed by a crystalliser |
| C. | Multiple effect evaporator |
| D. | Multiple effect evaporators followed by a crystalliser |
| Answer» D. Multiple effect evaporators followed by a crystalliser | |
| 344. |
_Reynold's analogy states that$? |
| A. | Nst α f |
| B. | Nst α NRe |
| C. | NNu α f |
| D. | NRe α f |
| Answer» B. Nst ≈í¬± NRe | |
| 345. |
_A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m².°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be$? |
| A. | Greater than that for uninsulated steam pipe |
| B. | Less than that of the uninsulated steam pipe |
| C. | Equal to that of the uninsulated steam pipe |
| D. | Less than the steam pipe with 5 cms insulation |
| Answer» C. Equal to that of the uninsulated steam pipe | |
| 346. |
_For specified tube outside diameter, higher BWG means higher$? |
| A. | Tube thickness |
| B. | Cross-sectional area |
| C. | Weight per unit length |
| D. | None of these |
| Answer» C. Weight per unit length | |
| 347. |
_In case of a supercooled solution, which is on the verge of crystallisation, the free energy of the solution as compared to that of the solid is$? |
| A. | More |
| B. | Less |
| C. | Same |
| D. | More or less; depends on the nature of solution |
| Answer» B. Less | |
| 348. |
_The actual temperature drop across the heating surface in an evaporator depends on the$? |
| A. | Feed |
| B. | Depth of liquid over heating surface |
| C. | Pressure difference between steam chest and vapour space |
| D. | All of the above |
| Answer» E. | |
| 349. |
_If Prandtl number is greater than the Schmidt number, then the$? |
| A. | Thermal boundary layer lies inside the concentration boundary layer |
| B. | Concentration boundary layer lies inside the thermal boundary layer |
| C. | Thermal & concentration boundary layers are of equal thickness |
| D. | Hydrodynamic(i.e., momentum)boundary layer is thicker than the other two |
| Answer» B. Concentration boundary layer lies inside the thermal boundary layer | |
| 350. |
Rate of heat transfer by vaporisation from pools of water is affected by the$? |
| A. | Nature of heating surface and distribution of bubbles |
| B. | Surface tension of water |
| C. | Viscosity of water |
| D. | All of the above |
| Answer» E. | |