MCQOPTIONS
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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.
| 401. |
The most conducive surface for dropwise condensation to occur is the __________ surface. |
| A. | coated |
| B. | oily |
| C. | glazed & polished |
| D. | smooth |
| Answer» C. glazed & polished | |
| 402. |
Which is the most suitable for the con-certration of highly concentrated solution? |
| A. | Open pan evaporation |
| B. | Long tube vertical evaporator |
| C. | Agitated film evaporator |
| D. | None of these |
| Answer» B. Long tube vertical evaporator | |
| 403. |
For small temperature difference, the heat transfer rate as per Newton's law of cooling is proportional to (where, Δt = excess temperature)$ |
| A. | Δt |
| B. | Δt2 |
| C. | Δt3 |
| D. | Δt |
| Answer» B. Œît2 | |
| 404. |
It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is$ |
| A. | 3.06 x l05 |
| B. | 6.12 x 105 |
| C. | 7.24 x 105 |
| D. | 9.08 x 105 |
| Answer» B. 6.12 x 105 | |
| 405. |
Planck's distribution law is valid for __________ bodies. |
| A. | black |
| B. | white |
| C. | coloured |
| D. | all (a), (b) & (c) |
| Answer» D. all (a), (b) & (c) | |
| 406. |
Calburn analogy is applicable for the value of Prandtl number from |
| A. | 0.001 to 1 |
| B. | 0.6 to 120 |
| C. | 0.5 to 5 |
| D. | 120 to 400 |
| Answer» C. 0.5 to 5 | |
| 407. |
A body cools down from 75°C to 70°C in 10 minutes. It will cool down from 70° C to 65° C in __________ minutes.$ |
| A. | 10 |
| B. | >10 |
| C. | <10 |
| D. | either (b) or (c), depends on the mass of the body |
| Answer» C. <10 | |
| 408. |
Stefen's block body radiation law can also be derived from __________ law. |
| A. | Kirchoffs |
| B. | Planck's |
| C. | Fourier's |
| D. | none of these |
| Answer» C. Fourier's | |
| 409. |
The film thickness for laminar film condensation on vertical surface __________ from top to bottom. |
| A. | cummulatively increases |
| B. | cummulatively decreases |
| C. | remains constant |
| D. | and the surface conductance increase |
| Answer» B. cummulatively decreases | |
| 410. |
The purpose of providing a 'catchall' in the vapor line of an evaporator is to |
| A. | create vacuum |
| B. | regulate the vapor flow |
| C. | vent the non-condensible gases |
| D. | arrest the entrained liquid |
| Answer» E. | |
| 411. |
Boiling point elevation for a strong and concentrated solution is found by Duhring's rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water. |
| A. | boiling point |
| B. | dynamic viscosity |
| C. | kinematic viscosity |
| D. | density |
| Answer» B. dynamic viscosity | |
| 412. |
The maximum heat transfer co-efficient from steam heating will be attained when the steam is |
| A. | supersaturated |
| B. | saturated |
| C. | wet |
| D. | none of these |
| Answer» C. wet | |
| 413. |
What is the absorptivity of a black body ? |
| A. | 1 |
| B. | 0 |
| C. | 0.78 |
| D. | 0.95 |
| Answer» B. 0 | |
| 414. |
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 | |
| 415. |
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 | |
| 416. |
Which of the following has maximum thermal conductivity at the same temperature? |
| A. | Steel |
| B. | Petrol |
| C. | Air |
| D. | All have the same conductivity |
| Answer» B. Petrol | |
| 417. |
1 BTU/hr.ft.°F is equal to __________ kcal/hr. m.°C.$ |
| A. | 1.49 |
| B. | 1 |
| C. | 4.88 |
| D. | none of these |
| Answer» B. 1 | |
| 418. |
Which of the following has the lowest overall heat transfer co-efficient ? |
| A. | Dowtherm |
| B. | Molten sodium |
| C. | Water |
| D. | Air |
| Answer» E. | |
| 419. |
Correction is applied to LMTD for __________ flow. |
| A. | parallel |
| B. | counter |
| C. | cross |
| D. | none of these |
| Answer» D. none of these | |
| 420. |
Which of the following has the minimum thermal conductivity ? |
| A. | Nitrogen |
| B. | Steel |
| C. | Carbon black |
| D. | Tar |
| Answer» B. Steel | |
| 421. |
Heat flux through several resistances in series in analogous to the current flowing through several |
| A. | resistances in parallel. |
| B. | capacitors in series. |
| C. | resistances in series. |
| D. | none of these. |
| Answer» D. none of these. | |
| 422. |
It is not preferable to use superheated steam in evaporators, because of its very |
| A. | high temperature |
| B. | high pressure |
| C. | low film co-efficient |
| D. | none of these |
| Answer» D. none of these | |
| 423. |
In a shell and tube heat exchanger, the shell side fluid velocity can not be changed by changing the |
| A. | tube layout |
| B. | tube diameter |
| C. | tube pitch |
| D. | no. of baffles |
| Answer» C. tube pitch | |
| 424. |
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. | |
| 425. |
Electromagnetic radiations propagate in vacuum with a velocity of __________ metre/second. |
| A. | 3 x l05 |
| B. | 3 x l08 |
| C. | 3 x l010 |
| D. | 3 x l012 |
| Answer» C. 3 x l010 | |
| 426. |
Fqra cold viscous feed, backward feed gives __________ than forward feed. |
| A. | a higher capacity |
| B. | a lower capacity |
| C. | lower economy |
| D. | none of these |
| Answer» B. a lower capacity | |
| 427. |
Crystallisation of solids from a homogeneous solution is a/an __________ process. |
| A. | exothermic |
| B. | mildly endothermic |
| C. | highly endothermic |
| D. | none of these |
| Answer» B. mildly endothermic | |
| 428. |
Steam is to be condensed in a shell and tube heat exchanger, 5 m long with a shell diameter of 1 m. Cooling water is to be used for removing the heat. Heat transfer co-efficient for the cooling water, whether on shell side or tube side is the same. The best arrangement is |
| A. | vertical heat exchanger with steam on tube side. |
| B. | vertical heat exchanger with steam on shell side. |
| C. | horizontal heat exchanger with steam on tube side. |
| D. | horizontal heat exchanger with steam on shell side. |
| Answer» C. horizontal heat exchanger with steam on tube side. | |
| 429. |
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 | |
| 430. |
Vibrations in the tubes of a shell and tube heat exchanger is induced due to the |
| A. | flow of fluid on the tube and shell sides. |
| B. | oscillations in the flow of shell/tube sides fluid. |
| C. | vibrations transmitted through piping and/or supports due to external reasons. |
| D. | all (a), (b) and (c) |
| Answer» E. | |
| 431. |
For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then |
| A. | hf = hd |
| B. | hf > hd |
| C. | hf < hd |
| D. | hf could be greater or smaller than hd |
| Answer» D. hf could be greater or smaller than hd | |
| 432. |
Maximum heat transfer rate is obtained in __________ flow. |
| A. | laminar |
| B. | turbulent |
| C. | creeping |
| D. | transition region |
| Answer» C. creeping | |
| 433. |
"The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium". This is __________ law. |
| A. | Kirchoffs |
| B. | Planck's |
| C. | Wien's displacement |
| D. | Stefan-Boltzman |
| Answer» B. Planck's | |
| 434. |
Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter) |
| A. | 0.2 D |
| B. | 0.5 D |
| C. | 0.66 D |
| D. | 0.80 D |
| Answer» B. 0.5 D | |
| 435. |
Dropwise condensation occurs on __________ surfaces. |
| A. | clean and dirt free |
| B. | smooth clean |
| C. | contaminated cooling |
| D. | polished |
| Answer» D. polished | |
| 436. |
Extremely large or small volumes of fluids are generally best routed through the shell side of a shell and tube heat exchanger, because of the |
| A. | less corrosion problems. |
| B. | flexibility possible in the baffle arrangement. |
| C. | low pressure drop. |
| D. | high heat transfer co-efficient. |
| Answer» C. low pressure drop. | |
| 437. |
At what value of Prandtl number, the hydrodynamic and thermal boundary layers are identical ? |
| A. | 0.5 |
| B. | 1 |
| C. | 1.5 |
| D. | 80 |
| Answer» C. 1.5 | |
| 438. |
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. | |
| 439. |
Steady state one dimensional heat flow by conduction as given by Fourier's low does not assume that |
| A. | there is no internal heat generation. |
| B. | boundary surfaces are isothermal. |
| C. | material is anisotropic. |
| D. | constant temperature gradient exists. |
| Answer» D. constant temperature gradient exists. | |
| 440. |
Thermal conductivities of most of the liquids __________ with rise in temperature. |
| A. | increases |
| B. | decreases |
| C. | remains unchanged |
| D. | may increase or decrease; depends on the liquid |
| Answer» C. remains unchanged | |
| 441. |
The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m2.K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m2.K. The overall heat transfer co-efficient at this time is |
| A. | 1200W/m2.K |
| B. | 894W/m2.K |
| C. | 333W/m2.K |
| D. | 287 W/m2.K |
| Answer» D. 287 W/m2.K | |
| 442. |
is called the __________ number |
| A. | Peclet |
| B. | Stanton |
| C. | Graetz |
| D. | none of these |
| Answer» D. none of these | |
| 443. |
Circulation pump is located below the evaporater to |
| A. | avoid cavitation. |
| B. | avoid frequent priming. |
| C. | create more suction head. |
| D. | none of these. |
| Answer» D. none of these. | |
| 444. |
It is not recommended to use a 1-2 shell and tube heat exchanger for a particular heat duty, whenever the LMTD correction factor is |
| A. | > 0.75 |
| B. | < 0.75 |
| C. | < 0.50 |
| D. | < 0.25 |
| Answer» C. < 0.50 | |
| 445. |
A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time$ |
| A. | t = 283 s |
| B. | t = 356 s |
| C. | t = 400 s |
| D. | t = 800 s |
| Answer» E. | |
| 446. |
At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ? |
| A. | 0.5 |
| B. | < 0.5 |
| C. | > 0.6 |
| D. | < 0.1 |
| Answer» D. < 0.1 | |
| 447. |
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. | t4 |
| B. | T4 |
| C. | 1/t4 |
| D. | 1/T4 |
| Answer» C. 1/t4 | |
| 448. |
Trap is used to remove __________ from steam pipe lines. |
| A. | steam |
| B. | condensate |
| C. | non-condensables |
| D. | none of these |
| Answer» C. non-condensables | |
| 449. |
In forced convection, the Nusselt number is a function of |
| A. | Re and Pr |
| B. | Re and Gr |
| C. | Pr and Gr |
| D. | Re and Sc |
| Answer» B. Re and Gr | |
| 450. |
The equation, (NSt x N2/3Pr) = f/2, is the __________ analogy. |
| A. | Colburn |
| B. | Reynolds |
| C. | Prandtl |
| D. | none of these. |
| Answer» B. Reynolds | |