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.
| 551. |
Heat produced when a steady state current, I passes through an electrical conductor having resistance, 'R' is |
| A. | IR |
| B. | I2R |
| C. | IR2 |
| D. | I2R2 |
| Answer» C. IR2 | |
| 552. |
Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for |
| A. | cube |
| B. | cylinder |
| C. | sphere |
| D. | equal for all the three |
| Answer» B. cylinder | |
| 553. |
'Fouling factor' used in the design of a multipass shell and tube heat exchanger is a |
| A. | non-dimensional factor. |
| B. | factor of safety. |
| C. | conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient. |
| D. | none of these. |
| Answer» C. conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient. | |
| 554. |
jH factor for heat transfer is not a function of the __________ number. |
| A. | Reynolds |
| B. | Nusselt |
| C. | Grashoff |
| D. | both (b) & (c) |
| Answer» E. | |
| 555. |
A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides |
| A. | higher economy |
| B. | lower capacity |
| C. | both (a) & (b) |
| D. | lower economy |
| Answer» B. lower capacity | |
| 556. |
For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it |
| A. | occupies smaller space. |
| B. | is more economical. |
| C. | is easy to operate and maintain. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 557. |
In the equation Q = UAΔt; Δt is |
| A. | geometric mean temperature difference. |
| B. | arithmetic mean temperature difference. |
| C. | logarithmic mean temperature difference. |
| D. | the difference of average bulk temperatures of hot and cold fluids. |
| Answer» D. the difference of average bulk temperatures of hot and cold fluids. | |
| 558. |
Nucleate boiling is promoted |
| A. | on polished surfaces |
| B. | on rough surfaces |
| C. | in the absence of agitation |
| D. | none of these |
| Answer» C. in the absence of agitation | |
| 559. |
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 | |
| 560. |
Controlling heat transfer film co-efficient is the one, which offers __________ resistance to heat transfer. |
| A. | no |
| B. | the least |
| C. | the largest |
| D. | lower |
| Answer» D. lower | |
| 561. |
If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows __________ law. |
| A. | hyperbolic |
| B. | parabolic |
| C. | linear |
| D. | logarithmic |
| Answer» D. logarithmic | |
| 562. |
Multiple effect evaporators ar used to |
| A. | increase the steam economy & decrease the capacity. |
| B. | increase the steam economy & the capacity. |
| C. | decrease the steam economy & the capacity. |
| D. | decrease the steam economy & increase the capacity. |
| Answer» C. decrease the steam economy & the capacity. | |
| 563. |
Kg of liquid evaporated per hour in an evaporator is defined as its |
| A. | capacity |
| B. | economy |
| C. | steam load |
| D. | none of these |
| Answer» B. economy | |
| 564. |
The Graetz number is concerned with the |
| A. | mass transfer between a gas and a liquid. |
| B. | absorption with chemical reaction. |
| C. | heat transfer in turbulent flow. |
| D. | heat transfer in laminar flow. |
| Answer» E. | |
| 565. |
A 2-4 heat exchanger involves |
| A. | only counter-flow of fluids. |
| B. | only parallel-flow of fluids. |
| C. | both counter and parallel-flow of the fluids. |
| D. | smaller pressure drop compared to 1-2 exchanger. |
| Answer» D. smaller pressure drop compared to 1-2 exchanger. | |
| 566. |
Presence of a non-condensing gas in a condensing vapour |
| A. | increases the rate of condensation. |
| B. | decreases thermal resistance. |
| C. | is desirable to increase the film co-efficient. |
| D. | none of these. |
| Answer» E. | |
| 567. |
The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K= 0.04 W/m.°K and thickness 0.16m is 10 W/m2. The temperature of the inside wall is - 5°C. The outside wall temperature is |
| A. | 25°C |
| B. | 30°C |
| C. | 35°C |
| D. | 40°C |
| Answer» D. 40¬∞C | |
| 568. |
In SI units, fouling factor is expressed in |
| A. | m2°K/W |
| B. | W/m2°K |
| C. | m2°K |
| D. | m°K/W |
| Answer» B. W/m2¬∞K | |
| 569. |
Boiling of milk in an open vessel is an example of __________ boiling. |
| A. | film |
| B. | sub-cooled |
| C. | saturated nucleate |
| D. | none of these |
| Answer» B. sub-cooled | |
| 570. |
For an ideal black body |
| A. | absorptivity = 1 |
| B. | reflectivity = 1 |
| C. | emissivity = 0 |
| D. | transmissivity = 1 |
| Answer» B. reflectivity = 1 | |
| 571. |
Heat transfer co-efficient (h) for a fluid flowing inside a clean pipe is given by This is valid for the value of NRe equal to |
| A. | < 2100 |
| B. | 2100-4000 |
| C. | > 4000 |
| D. | > 10000 |
| Answer» E. | |
| 572. |
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. | |
| 573. |
Nusselt number is the ratio of the temperature gradient at the wall to |
| A. | temperature difference |
| B. | heat flux |
| C. | that across the entire pipe |
| D. | none of these |
| Answer» D. none of these | |
| 574. |
In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side __________ the heat transfer rate. |
| A. | increases |
| B. | decreases |
| C. | does not affect |
| D. | may increase or decrease, depends on the type of baffle |
| Answer» B. decreases | |
| 575. |
The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation. |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | may increase or decrease ; depends on the material |
| Answer» E. | |
| 576. |
If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length |
| A. | ha = hl |
| B. | ha = 2hl |
| C. | ha = 0.5 hl |
| D. | ha = 0.75 hl |
| Answer» C. ha = 0.5 hl | |
| 577. |
For concentrating an aqueous solution of a material like anhydrous Na2SO4, whose solubility decreases with rise in temperature, the most suitable evaporator is a __________ evaporator. |
| A. | high pressure |
| B. | vacuum |
| C. | backward feed |
| D. | none of these |
| Answer» C. backward feed | |
| 578. |
The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are |
| A. | (COP)R = (COP)HP = 0.6 |
| B. | (COP)R = 2.5; (COP)HP = 1.5 |
| C. | (COP)R = 1.5; (COP)HP = 2.5 |
| D. | (COP)R = (COP)HP = 2.5 |
| Answer» D. (COP)R = (COP)HP = 2.5 | |
| 579. |
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 | |
| 580. |
The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe whose surface temperature remains constant is |
| A. | 1.66 |
| B. | 88.66 |
| C. | 3.66 |
| D. | dependent on NRe only |
| Answer» D. dependent on NRe only | |
| 581. |
With the increase of temperature, the Col-burn jH factor |
| A. | increases. |
| B. | decreases. |
| C. | remains unchanged. |
| D. | may increase or decrease ; depending on temperature. |
| Answer» B. decreases. | |
| 582. |
Film boiling is usually not desired in commercial equipments, because |
| A. | the heat transfer rate is low in view of the large temperature drop. |
| B. | it is difficult to maintain. |
| C. | it is not economic. |
| D. | none of these. |
| Answer» B. it is difficult to maintain. | |
| 583. |
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 | |
| 584. |
The advantage of backward feed multiple effect evaporators over forward feed units is that |
| A. | heat sensitive material can be handled. |
| B. | there is no additional cost of pumping. |
| C. | most concentrated liquid is at highest temperature. |
| D. | equal heat transfer co-efficients exist in various effects. |
| Answer» D. equal heat transfer co-efficients exist in various effects. | |
| 585. |
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. | |
| 586. |
In a heat exchanger, floating head is provided to |
| A. | facilitate cleaning of the exchanger. |
| B. | increase the heat transfer area. |
| C. | relieve stresses caused by thermal expansion. |
| D. | increase log mean temperature gradient. |
| Answer» D. increase log mean temperature gradient. | |
| 587. |
In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid. |
| A. | nucleate |
| B. | pool |
| C. | low pressure |
| D. | none of these |
| Answer» C. low pressure | |
| 588. |
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. | |
| 589. |
Film boiling occurs at __________ pressure. |
| A. | atmospheric |
| B. | sub-atmospheric |
| C. | negative |
| D. | very high |
| Answer» E. | |
| 590. |
Reynold's analogy states that |
| A. | Nst α f |
| B. | Nst α NRe |
| C. | NNu α f |
| D. | NRe α f |
| Answer» B. Nst Œ± NRe | |
| 591. |
Which one gives the monochromatic emissive power for black body radiation ? |
| A. | Planck's law |
| B. | Kirchhoffs law |
| C. | Wien's law |
| D. | Stefan-Boltzman law |
| Answer» B. Kirchhoffs law | |
| 592. |
Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is |
| A. | in the central core of the fluid. |
| B. | uniformly distributed throughout the fluid. |
| C. | mainly confined to a thin film of fluid near the surface. |
| D. | none of these. |
| Answer» D. none of these. | |
| 593. |
Which is the most suitable for cold viscous feed? |
| A. | Forward feed |
| B. | Backward feed |
| C. | Mixed feed |
| D. | Parallel feed |
| Answer» C. Mixed feed | |
| 594. |
The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation. |
| A. | greater than |
| B. | lower than |
| C. | is same as |
| D. | half |
| Answer» C. is same as | |
| 595. |
Baffles in the shell side of a shell and tube heat exchanger |
| A. | increase the cross-section of the shell side liquid. |
| B. | force the liquid to flow parallel to the bank. |
| C. | increase the shell side heat transfer co-efficient. |
| D. | decrease the shell side heat transfer co-efficient. |
| Answer» D. decrease the shell side heat transfer co-efficient. | |
| 596. |
Grashoff number, which is defined as g . β(Ts - T∞) ρ2. L3/μ2, is proportional to the ratio of buoyancy force to __________ force. |
| A. | viscous |
| B. | elastic |
| C. | inertial |
| D. | none of these |
| Answer» B. elastic | |
| 597. |
According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor) |
| A. | 2f |
| B. | f |
| C. | f/2 |
| D. | f/4 |
| Answer» D. f/4 | |
| 598. |
Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger? |
| A. | Corrosiveness & fouling characteristics |
| B. | pressure |
| C. | viscosity |
| D. | density |
| Answer» E. | |
| 599. |
For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number) |
| A. | NPr |
| B. | NPr1/3 |
| C. | NPr-1 |
| D. | NPr-1/3 |
| Answer» C. NPr-1 | |
| 600. |
Baffles are provided in heat exchangers to increase the |
| A. | fouling factor |
| B. | heat transfer area |
| C. | heat transfer co-efficient |
| D. | heat transfer rate |
| Answer» D. heat transfer rate | |