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.
| 451. |
The equation, , corrosponds to __________ analogy. |
| A. | Von-Karmann |
| B. | Reynolds |
| C. | Colburn |
| D. | Prandtl |
| Answer» E. | |
| 452. |
Which of the following is the most widely used heat insulating material for pipelines carrying steam ? |
| A. | Tar dolomite bricks followed by asbestos. |
| B. | Fireclay refractory followed by aluminium sheet. |
| C. | Cotton followed by aluminium foil. |
| D. | 85% magnesia cement and glass wool. |
| Answer» E. | |
| 453. |
The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface) |
| A. | K/h0 |
| B. | 2K/h0 |
| C. | h0/K |
| D. | h0/2K |
| Answer» C. h0/K | |
| 454. |
If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will |
| A. | increase by 1.8 times |
| B. | decrease by 22 |
| C. | increase by 216 |
| D. | remain unchanged |
| Answer» D. remain unchanged | |
| 455. |
What is the thermal conductivity of a perfect heat insulator ? |
| A. | zero |
| B. | one |
| C. | ‚àû |
| D. | between 0 and ‚àû |
| Answer» B. one | |
| 456. |
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 | |
| 457. |
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. | |
| 458. |
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 | |
| 459. |
For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is |
| A. | Nu = 0.023 Re0.8 . Pr0.4 |
| B. | Nu = Gz |
| C. | Nu = Gz |
| D. | Nu = 2Gz0.5 |
| Answer» D. Nu = 2Gz0.5 | |
| 460. |
Electro-magnetic spectrum range, which is important for radiation varies from __________ microns. |
| A. | 1 to 100 |
| B. | 0.5 to 50 |
| C. | 10 to 100 |
| D. | 100 to 1000 |
| Answer» C. 10 to 100 | |
| 461. |
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 | |
| 462. |
The unit of heat transfer co-efficient is |
| A. | BTU/hr. ft2°F |
| B. | BTU/hr. °F. ft. |
| C. | BTU/hr. °F |
| D. | BTU/hr. ft |
| Answer» B. BTU/hr. ¬∞F. ft. | |
| 463. |
Prandtl and Reynold's analogies are identical for Prandtl number value of |
| A. | 0 |
| B. | 0.5 |
| C. | 1 |
| D. | 5 |
| Answer» D. 5 | |
| 464. |
View factor is important in heat transfer by |
| A. | steady state conduction |
| B. | natural convection |
| C. | forced convection |
| D. | radiation |
| Answer» E. | |
| 465. |
Indirect contact heat exchangers are preferred over direct contact heat exchangers, because |
| A. | heat transfer co-efficient are high. |
| B. | there is no risk of contamination. |
| C. | there is no mist formation. |
| D. | cost of equipment is lower. |
| Answer» C. there is no mist formation. | |
| 466. |
Which of the following has the minimum absorptivity ? |
| A. | Aluminium foil |
| B. | Coal dust |
| C. | Refractory bricks |
| D. | Iron plates |
| Answer» B. Coal dust | |
| 467. |
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 | |
| 468. |
For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | passes through a maxima |
| Answer» E. | |
| 469. |
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 |
| Answer» B. E/C | |
| 470. |
Unsteady state heat conduction occurs, when |
| A. | temperature distribution is independent of time. |
| B. | temperature distribution is dependent on time. |
| C. | heat flows in one direction only. |
| D. | three dimensional heat flow is concerned. |
| Answer» C. heat flows in one direction only. | |
| 471. |
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 (a), (b) and (c). |
| Answer» E. | |
| 472. |
In Biot number, the characteristic length used is the ratio of the __________ of the solid. |
| A. | volume to surface area |
| B. | perimeter to surface area |
| C. | surface area to volume |
| D. | surface area to perimeter |
| Answer» B. perimeter to surface area | |
| 473. |
In a cooling tower, water becomes cool by |
| A. | loosing sensible heat. |
| B. | heat transfer to surroundings. |
| C. | vaporisation due to heat loss to air. |
| D. | loosing latent heat. |
| Answer» B. heat transfer to surroundings. | |
| 474. |
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 | |
| 475. |
__________ 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 | |
| 476. |
In case of heat flow by conduction for a cylindrical body with an internal heat source, the nature of temperature distribution is |
| A. | linear |
| B. | hyperbolic |
| C. | parabolic |
| D. | none of these |
| Answer» D. none of these | |
| 477. |
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 | |
| 478. |
Finned tube heat exchangers |
| A. | give larger area per tube. |
| B. | use metal fins of low thermal conductivity. |
| C. | facilitate very large temperature drop through tube wall. |
| D. | are used for smaller heat load. |
| Answer» B. use metal fins of low thermal conductivity. | |
| 479. |
A process stream of dilute aqueous solution flowing at the rate of10 Kg.s-1 is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 Kg.s-1. A 1 - 1 shell and tube heat exchanger is available. The best arrangement is$ |
| A. | counter flow with process stream on shell side. |
| B. | counter flow with process stream on tube side. |
| C. | parallel flow with process stream on shell side. |
| D. | parallel flow with process stream on tube side. |
| Answer» B. counter flow with process stream on tube side. | |
| 480. |
The heat flux in the nucleate boiling regimes is proportional to (where, ΔT = excess temperature)$ |
| A. | (ΔT)2 |
| B. | (ΔT)4 |
| C. | (ΔT)3 |
| D. | (ΔT) |
| Answer» D. (ŒîT) | |
| 481. |
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 | |
| 482. |
What is the unit of thermal conductivity ? |
| A. | Kcal/hr. m2 °C |
| B. | Kcal/hr.m.°C |
| C. | Kcal/hr.m |
| D. | Kcal/hr. °C |
| Answer» C. Kcal/hr.m | |
| 483. |
Absorptivity and refletivity of a perfect black body are respectively |
| A. | 1 and 0 |
| B. | 0 and 1 |
| C. | 1 and ‚àû |
| D. | 0 and 0.5 |
| Answer» B. 0 and 1 | |
| 484. |
When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids ? |
| A. | At high fluid velocity |
| B. | At low velocity |
| C. | When fluid flows past a smooth surface |
| D. | None of these |
| Answer» B. At low velocity | |
| 485. |
Leidenfrost point is a term concerned with the |
| A. | condensation of the saturated vapor on a cold surface. |
| B. | concentration of a corrosive solution by evaporation. |
| C. | heat transfer between two highly viscous liquids. |
| D. | boiling of a liquid on a hot surface. |
| Answer» E. | |
| 486. |
Loss of heat from untagged steam pipe to the ambient air is by |
| A. | conduction |
| B. | convection |
| C. | radiation |
| D. | all (a), (b) & (c) |
| Answer» E. | |
| 487. |
Overall heat transfer co-efficient of a particular tube is U1. If the same tube with some dirt deposited on either side has coefficient U2, then |
| A. | U1 = U2 |
| B. | U2 > U1 |
| C. | U1 > U2 |
| D. | U1 = dirt factor - U2 |
| Answer» B. U2 > U1 | |
| 488. |
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) | |
| 489. |
(NGr x NPr) is called the __________ number. |
| A. | Graetz |
| B. | Reyleigh |
| C. | Nusselt |
| D. | Stanton |
| Answer» C. Nusselt | |
| 490. |
With increase in temperature, the total emissivity of conductors |
| A. | increases |
| B. | decreases |
| C. | remains same |
| D. | decreases linearly |
| Answer» B. decreases | |
| 491. |
The unit of conductance in SI unit is |
| A. | W/m |
| B. | W/m2 |
| C. | W/°K |
| D. | W/m°K |
| Answer» D. W/m¬∞K | |
| 492. |
A perfect black body is a perfect __________ of radiation. |
| A. | absorber |
| B. | emitter |
| C. | both (a) & (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 493. |
The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m2. The approximate surface temperature (K) is (Stefan-Boltzman constant = 5.67xl0-8 W/m2.K4) |
| A. | 1000 |
| B. | 727 |
| C. | 800 |
| D. | 1200 |
| Answer» B. 727 | |
| 494. |
Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity ? |
| A. | aluminium foil |
| B. | refractory bricks |
| C. | iron plate |
| D. | coke breeze |
| Answer» E. | |
| 495. |
Which of the following is concerned with both heat and mass transfer ? |
| A. | Lewis relationship |
| B. | Nusselt number |
| C. | Kutateladze number |
| D. | Froude number |
| Answer» B. Nusselt number | |
| 496. |
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 | |
| 497. |
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 | |
| 498. |
In a gas-liquid shell and tube heat exchanger, the |
| A. | presence of a non-condensible gas decreases the condensing film co-efficient. |
| B. | gases under high pressure are routed through the tube side, because high pressure gases are corrosive in nature. |
| C. | gases to be heated/cooled is normally routed through the shell side, because the corrosion caused by the cooling water or steam condensate remain localised to the tubes. |
| D. | all 'a', 'b' & 'c' |
| Answer» E. | |
| 499. |
Which of the following is correct ? |
| A. | Rate = Driving force x Resistance |
| B. | Driving force = Rate x Resistance |
| C. | Resistance = Driving force x Rate |
| D. | Rate = Resistance/Driving force |
| Answer» C. Resistance = Driving force x Rate | |
| 500. |
Mechanical recompression evaporation is used in the production of |
| A. | alcohol |
| B. | distilled water |
| C. | salt |
| D. | fruits jam |
| Answer» C. salt | |