MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 640 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 351. |
Convective heat transfer, in which heat is transferred by movement of warmed matter is described by |
| A. | Fourier's law |
| B. | Newton's law of cooling |
| C. | Fick's law |
| D. | none of these |
| Answer» C. Fick's law | |
| 352. |
Multiple effect evaporators are commonly used in the manufacture of P. Paper Q. Superphosphate R. Sugar S. Fats |
| A. | P and Q |
| B. | P and R |
| C. | P and S |
| D. | R and S |
| Answer» D. R and S | |
| 353. |
The purpose of providing bleed points in the evaporator is to |
| A. | admit the feed |
| B. | remove the product |
| C. | facilitate removal of non-condensable gases |
| D. | create vacuum |
| Answer» D. create vacuum | |
| 354. |
In a multiple effect evaporator, the effect of boiling point elevation is to |
| A. | reduce the capacity |
| B. | reduce the economy |
| C. | increase the economy |
| D. | none of these |
| Answer» B. reduce the economy | |
| 355. |
For a multipass shell and tube heat exchanger, the LMTD correction factor is always |
| A. | 1 |
| B. | > 1 |
| C. | < 1 |
| D. | between 1 & 2 |
| Answer» D. between 1 & 2 | |
| 356. |
A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to |
| A. | d0.8 |
| B. | d-0.2 |
| C. | d-1 |
| D. | d-1.8 |
| Answer» C. d-1 | |
| 357. |
The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by __________ times, when the number of tube passes is increased to 8. |
| A. | 20.8 |
| B. | 40.8 |
| C. | 40.4 |
| D. | 20.4 |
| Answer» C. 40.4 | |
| 358. |
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. | |
| 359. |
As the difference between the wall temperature and bulk temperature increases, the boiling heat transfer co-efficient |
| A. | continues to increase. |
| B. | continues to decrease. |
| C. | goes through a minimum. |
| D. | goes through a maximum. |
| Answer» D. goes through a maximum. | |
| 360. |
Heat flux is the time rate of heat transfer per unit |
| A. | length |
| B. | area |
| C. | volume |
| D. | none of these |
| Answer» C. volume | |
| 361. |
Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface ? |
| A. | Liquid density |
| B. | Liquid viscosity |
| C. | Hot surface temperature |
| D. | Interfacial tension |
| Answer» E. | |
| 362. |
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 | |
| 363. |
For what value of Prandtl number, the Col-burn analogy is valid ? |
| A. | 0.06 to 120 |
| B. | 0.6 to 120 |
| C. | 1 to 103 |
| D. | l to 50 |
| Answer» C. 1 to 103 | |
| 364. |
Temperature profile in steady state heat transfer is |
| A. | asymptotic |
| B. | hyperbolic |
| C. | parabolic |
| D. | linear |
| Answer» E. | |
| 365. |
Fourier's law of heat conduction applies to __________ surfaces. |
| A. | isothermal |
| B. | non-isothermal |
| C. | both (a) and (b) |
| D. | neither (a) and (b) |
| Answer» D. neither (a) and (b) | |
| 366. |
In SI units, thermal conductivity is expressed in |
| A. | Watt/m.°K |
| B. | Watt/m2. °K |
| C. | Watt/m2. °K |
| D. | Watt/m4. °K |
| Answer» B. Watt/m2. ¬∞K | |
| 367. |
Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer co-efficient is 3k/l. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade ?$ |
| A. | 35.5 |
| B. | 43.75 |
| C. | 81.25 |
| D. | 48.25 |
| Answer» D. 48.25 | |
| 368. |
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. | |
| 369. |
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. | |
| 370. |
The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter (D) as$ |
| A. | (D)-1.8 |
| B. | (D))-0.2 |
| C. | (D)0.2 |
| D. | (D)1.8 |
| Answer» C. (D)0.2 | |
| 371. |
An ejector is used to |
| A. | increase pressure |
| B. | increase temperature |
| C. | remove condensate |
| D. | none of these |
| Answer» E. | |
| 372. |
Double pipe heat exchangers are preferably useful, when |
| A. | high viscosity liquid is to be cooled. |
| B. | requirement of heat transfer area is low. |
| C. | overall heat transfer co-efficient is very high. |
| D. | a corrosive liquid is to be heated. |
| Answer» C. overall heat transfer co-efficient is very high. | |
| 373. |
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 | |
| 374. |
Vent pipes are provided in a condenser to |
| A. | remove non-condensable gases. |
| B. | purge the condenser. |
| C. | facilitate easy cleaning of tubes. |
| D. | none of these. |
| Answer» B. purge the condenser. | |
| 375. |
The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe ) |
| A. | K/h0 |
| B. | 2K/h0 |
| C. | hi/K |
| D. | 2hi/K |
| Answer» B. 2K/h0 | |
| 376. |
__________ paint has the minimum absorption co-efficient. |
| A. | Black |
| B. | White lead |
| C. | Grey |
| D. | Light cream |
| Answer» C. Grey | |
| 377. |
One kilogram of water at 0°C is changed to superheated steam of one atm pressure and 300° C. The major heat consumption in the process will be to$ |
| A. | heat the water from 0°C to 100°C. |
| B. | evaporate the water. |
| C. | to superheat the steam. |
| D. | data insufficient, can't be predicted |
| Answer» C. to superheat the steam. | |
| 378. |
The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid$ |
| A. | its evaporation loss |
| B. | excessive corrosion |
| C. | uneconomic LMTD |
| D. | decrease in heat exchanger efficiency |
| Answer» C. uneconomic LMTD | |
| 379. |
A body is called grey if the monochromatic emissivity of the body is |
| A. | zero |
| B. | unity |
| C. | same for all wavelengths |
| D. | different for all wavelengths |
| Answer» D. different for all wavelengths | |
| 380. |
The separation of liquid droplets from the vapor is done by a/an __________ , in the evaporators. |
| A. | steam ejector |
| B. | entrainment separator |
| C. | compressor |
| D. | vacuum pump |
| Answer» C. compressor | |
| 381. |
Heat transfer by radiation between two bodies at T1 & T2 and in an ambient temperature of Ta°C depends on$ |
| A. | T1 - T2 |
| B. | T1 - Ta |
| C. | T2 - Ta |
| D. | none of these |
| Answer» E. | |
| 382. |
If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is |
| A. | 1 |
| B. | 2 |
| C. | 43497 |
| D. | 4 |
| Answer» C. 43497 | |
| 383. |
The non-dimensional temperature gradient in a liquid at the wall of a pipe is the |
| A. | heat flux |
| B. | Nusselt number |
| C. | Prandtl number |
| D. | Schmidt number |
| Answer» B. Nusselt number | |
| 384. |
Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling ? |
| A. | Square pitch |
| B. | Triangular pitch |
| C. | Diagonal square pitch |
| D. | None of these |
| Answer» C. Diagonal square pitch | |
| 385. |
A black body when hot, emits heat radiation of __________ wavelengths. |
| A. | small |
| B. | large |
| C. | all |
| D. | one fixed |
| Answer» D. one fixed | |
| 386. |
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 | |
| 387. |
The advantage of using a 1 - 2 shell and tube heat exchanger over a 1 - 1 shell and tube heat exchanger is |
| A. | lower tube side pressure drop. |
| B. | lower shell side pressure drop. |
| C. | higher tube side heat transfer co-efficient. |
| D. | higher shell side heat transfer co-efficient. |
| Answer» D. higher shell side heat transfer co-efficient. | |
| 388. |
In a shell and tube heat exchanger, square pitch compared to triangular pitch |
| A. | gives a higher shell side pressure drop. |
| B. | gives a lower shell side pressure drop. |
| C. | can pack more surface area into a shell of given diameter. |
| D. | none of these. |
| Answer» B. gives a lower shell side pressure drop. | |
| 389. |
In forced convection, the heat transfer depends on |
| A. | Re, Pr |
| B. | Re, Gr |
| C. | mainly Gr |
| D. | Re only |
| Answer» B. Re, Gr | |
| 390. |
In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate. |
| A. | geometric |
| B. | arithmetic |
| C. | logarithmic |
| D. | either (a), (b) or (c) |
| Answer» D. either (a), (b) or (c) | |
| 391. |
Multiple effect evaporation accounts for |
| A. | steam economy |
| B. | lower operating costs |
| C. | investment economy |
| D. | none of these |
| Answer» B. lower operating costs | |
| 392. |
In regenerative air preheater (as practised in heating of coke ovens), the heat is transferred |
| A. | through a metallic wall. |
| B. | by direct contact of hot flue gas with air. |
| C. | by heating an intermediate material (like chequor bricks) and then heating the air from this hot material. |
| D. | none of these. |
| Answer» D. none of these. | |
| 393. |
Radiator of an automobile engine is a __________ type of heat exchanger. |
| A. | co-current |
| B. | cross-current |
| C. | counter-current |
| D. | direct contact |
| Answer» E. | |
| 394. |
For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally |
| A. | decreases |
| B. | increases |
| C. | remains unchanged |
| D. | increases exponentially |
| Answer» B. increases | |
| 395. |
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. | |
| 396. |
Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law. |
| A. | Stefan's |
| B. | Dalton's |
| C. | Wien's |
| D. | Kirchoffs |
| Answer» D. Kirchoffs | |
| 397. |
The driving potential for the crystal growth during crystallisation is the __________ of the solution. |
| A. | concentration |
| B. | viscosity |
| C. | super-saturation |
| D. | density |
| Answer» D. density | |
| 398. |
In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid. |
| A. | equal to |
| B. | more than |
| C. | less than |
| D. | either more or less than (depending upon the fluid) |
| Answer» B. more than | |
| 399. |
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 | |
| 400. |
Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is |
| A. | 1 |
| B. | < 1 |
| C. | > 1 |
| D. | > 5 |
| Answer» C. > 1 | |