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.
| 401. |
In Biot number, the characteristic length used is the ratio of the __________ of the solid.$? |
| A. | Volume to surface area |
| B. | Perimeter to surface area |
| C. | Surface area to volume |
| D. | Surface area to perimeter |
| Answer» B. Perimeter to surface area | |
| 402. |
The main purpose of providing fins on heat transfer surface is to increase the$? |
| A. | Temperature gradient |
| B. | Mechanical strength of the equipment |
| C. | Heat transfer area |
| D. | Heat transfer co-efficient |
| Answer» D. Heat transfer co-efficient | |
| 403. |
Finned tube heat exchangers$? |
| A. | Give larger area per tube |
| B. | Use metal fins of low thermal conductivity |
| C. | Facilitate very large temperature drop through tube wall |
| D. | Are used for smaller heat load |
| Answer» B. Use metal fins of low thermal conductivity | |
| 404. |
Which of the following is the most widely used heat insulating material for pipelines carrying steam?$? |
| 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. | |
| 405. |
In a laboratory test run, the rate of drying was found to be 0.5 x 10-3 kg/m².s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.08 on a dry basis. A tray dryer is used to dry 100 kg (dry basis) of the same material under identical conditions. The surface area of the material is 0.04 m²/kg of dry solid. The time required (in seconds) to reduce the moisture content of the solids from 0.3 to 0.2 (dry basis) is$? |
| A. | 2000 |
| B. | 4000 |
| C. | 5000 |
| D. | 6000 |
| Answer» D. 6000 | |
| 406. |
Which of the following has the lowest Prandtl number?$? |
| A. | Molten sodium (a coolant used in fast breeder reactor) |
| B. | Water |
| C. | Transformer oil |
| D. | Dilute H‚ÇÇSO‚ÇÑ |
| Answer» B. Water | |
| 407. |
When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids?$? |
| A. | At high fluid velocity |
| B. | At low velocity |
| C. | When fluid flows past a smooth surface |
| D. | None of these |
| Answer» B. At low velocity | |
| 408. |
An ejector is used to$? |
| A. | Increase pressure |
| B. | Increase temperature |
| C. | Remove condensate |
| D. | None of these |
| Answer» E. | |
| 409. |
Prandtl and Reynold's analogies are identical for Prandtl number value of$? |
| A. | 0 |
| B. | 0.5 |
| C. | 1 |
| D. | 5 |
| Answer» D. 5 | |
| 410. |
A dephlegmator is a$? |
| A. | Total condenser |
| B. | Vacuum evaporator |
| C. | Partial condenser |
| D. | Double pipe heat exchanger |
| Answer» D. Double pipe heat exchanger | |
| 411. |
A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun?? |
| A. | Yellow paint |
| B. | White paint |
| C. | Black paint |
| D. | Grey paint |
| Answer» D. Grey paint | |
| 412. |
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 | |
| 413. |
1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m² and the overall heat transfer co-efficient to the liquid is 1500 W/m².°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be? |
| A. | 15 min |
| B. | 22 min |
| C. | 44 min |
| D. | 51 min |
| Answer» E. | |
| 414. |
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 | |
| 415. |
In a forward feed multiple effect evaporator, the pressure is? |
| A. | Highest in last effect |
| B. | Lowest in last effect |
| C. | Same in all effects |
| D. | Dependent on the number of effects |
| Answer» C. Same in all effects | |
| 416. |
The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is? |
| A. | Nusselt number |
| B. | Sherwood number |
| C. | Schmidt number |
| D. | Stanton number |
| Answer» D. Stanton number | |
| 417. |
Correction is applied to LMTD for __________ flow.? |
| A. | Parallel |
| B. | Counter |
| C. | Cross |
| D. | None of these |
| Answer» D. None of these | |
| 418. |
Thermal diffusivity of a material? |
| A. | Has the unit m² /sec |
| B. | Is defined as K/ρ . Cp |
| C. | Is the ratio of thermal conductivity to thermal capacity |
| D. | All of the above |
| Answer» E. | |
| 419. |
In a forward feed multiple effect evaporator unit? |
| A. | Viscosity of liquid is highest in first effect |
| B. | Transfer from effect to effect is done by pumps |
| C. | No pump is required to withdraw the product from the last effect |
| D. | None of these |
| Answer» E. | |
| 420. |
Which of the following parameters is increased by use of finned tube in a multipass shell and tube heat exchanger?? |
| A. | Tube side pressure drop and the heat transfer rate |
| B. | Convective heat transfer co-efficient |
| C. | Effective tube surface area for convective heat transfer |
| D. | All of the above |
| Answer» E. | |
| 421. |
The purpose of providing expansion bellows in the shell of tubular exchanger is to? |
| A. | Increase the heating load |
| B. | Impart structural strength |
| C. | Account for the uneven expansion of shell and tube bundles |
| D. | Facilitate increase of shell length, if needed |
| Answer» D. Facilitate increase of shell length, if needed | |
| 422. |
__________ paint has the minimum absorption co-efficient.? |
| A. | Black |
| B. | White lead |
| C. | Grey |
| D. | Light cream |
| Answer» C. Grey | |
| 423. |
Overall thermal resistance for conductive heat transfer through a series of flat resistances is equal to the? |
| A. | Maximum resistance in the series |
| B. | Sum of all resistances |
| C. | Average of all resistances |
| D. | Minimum resistance presents in the series |
| Answer» C. Average of all resistances | |
| 424. |
LMTD for counterflow and prallel flow heat exchanger will be the same, when the? |
| A. | Cold fluid is heated to a certain temperature by condensing steam (isothermal fluid) |
| B. | Outlent temperature of both the hot and cold fluid are same |
| C. | Outlet temperature of hot fluid is less than the outlet temperature of the cold fluid |
| D. | None of these |
| Answer» B. Outlent temperature of both the hot and cold fluid are same | |
| 425. |
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 | |
| 426. |
Which of the following has the minimum absorptivity?? |
| A. | Aluminium foil |
| B. | Coal dust |
| C. | Refractory bricks |
| D. | Iron plates |
| Answer» B. Coal dust | |
| 427. |
In forced circulation, the heating element is injected? |
| A. | Internally |
| B. | Externally |
| C. | Both A and B |
| D. | Neither A nor B |
| Answer» B. Externally | |
| 428. |
Which of the following has the lowest Prandtl number?? |
| A. | Molten sodium (a coolant used in fast breeder reactor) |
| B. | Water |
| C. | Transformer oil |
| D. | Dilute H‚ÇÇSO‚ÇÑ |
| Answer» B. Water | |
| 429. |
Prandtl and Reynold's analogies are identical for Prandtl number value of? |
| A. | 0 |
| B. | 0.5 |
| C. | 1 |
| D. | 5 |
| Answer» D. 5 | |
| 430. |
A dephlegmator is a? |
| A. | Total condenser |
| B. | Vacuum evaporator |
| C. | Partial condenser |
| D. | Double pipe heat exchanger |
| Answer» D. Double pipe heat exchanger | |
| 431. |
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 | |
| 432. |
An ejector is used to? |
| A. | Increase pressure |
| B. | Increase temperature |
| C. | Remove condensate |
| D. | None of these |
| Answer» E. | |
| 433. |
Heat sensitive materials can be concentrated in an evaporator employing? |
| A. | Vacuum |
| B. | High pressure |
| C. | High residence time |
| D. | None of these |
| Answer» B. High pressure | |
| 434. |
With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer? |
| A. | Decreases |
| B. | Increases |
| C. | Increases exponentially |
| D. | Remains unaffected |
| Answer» B. Increases | |
| 435. |
The critical radius 'r' of insulation on a pipe is given by? |
| A. | r = 2k/h |
| B. | r = k/h |
| C. | r = k/2h |
| D. | r = h/k |
| Answer» C. r = k/2h | |
| 436. |
In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)? |
| A. | α = 1; ε ≠1 |
| B. | α ≠1, ε = 1 |
| C. | α ≠1, ε ≠1 |
| D. | α = 1; ε = 1 |
| Answer» E. | |
| 437. |
Steam is routed through the tube in case of a __________ evaporator.? |
| A. | Basket type |
| B. | Horizontal tube |
| C. | Short tube vertical |
| D. | Long tube vertical |
| Answer» C. Short tube vertical | |
| 438. |
Corrosiveness of steam condensate is due to the presence of? |
| A. | CO‚ÇÇ |
| B. | Dissolved O‚ÇÇ |
| C. | Both A & B |
| D. | Neither A nor B |
| Answer» D. Neither A nor B | |
| 439. |
Maximum heat transfer rate is obtained in __________ flow.? |
| A. | Laminar |
| B. | Turbulent |
| C. | Creeping |
| D. | Transition region |
| Answer» C. Creeping | |
| 440. |
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 | |
| 441. |
jH factor for heat transfer is not a function of the __________ number.? |
| A. | Reynolds |
| B. | Nusselt |
| C. | Grashoff |
| D. | Both B & C |
| Answer» E. | |
| 442. |
When warm and cold liquids are mixed, the heat transfer is mainly by? |
| A. | Conduction |
| B. | Convection |
| C. | Radiation |
| D. | Both A & C |
| Answer» C. Radiation | |
| 443. |
For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are? |
| A. | Same |
| B. | Different |
| C. | Never different |
| D. | Linearly related |
| Answer» C. Never different | |
| 444. |
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 | |
| 445. |
Maximum heat transfer rate is achieved in __________ flow.? |
| A. | Co-current |
| B. | Counter-current |
| C. | Turbulent |
| D. | Laminar |
| Answer» D. Laminar | |
| 446. |
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 | |
| 447. |
In the free convection regime of pool boiling, the heat flux is proportional to? |
| A. | Δt1/2 |
| B. | Δt2 |
| C. | Δt5/4 |
| D. | Δt |
| Answer» D. ≈í√Æt | |
| 448. |
Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is? |
| A. | 0.1 |
| B. | >1 |
| C. | < 1 |
| D. | L |
| Answer» B. >1 | |
| 449. |
In a single effect evaporator, the economy is? |
| A. | 1 |
| B. | < 1 |
| C. | > 1 |
| D. | None of these |
| Answer» C. > 1 | |
| 450. |
Which type of heat exchanger is preferred for heavy heat loads?? |
| A. | Double pipe |
| B. | Plate fine |
| C. | Series and parallel set of shell and tube |
| D. | None of these |
| Answer» D. None of these | |