chemical engineering MCQs – Page 196

Practise multiple-choice questions from chemical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering Mcqs
3901. The range of electromagnetic spectrum important in heat transfer by radiation is ______________ microns?
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A. 0.5-50

B. 100-1000

C. 0.38-0.78

D. May-50

3902. The non-dimensional temperature gradient in a liquid at the wall of a pipe is the ____________________?
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A. Prandtl number

B. Heat flux

C. Schmidt number

D. Nusselt number

3903. With increase in temperature, the thermal conductivity of fresh lubricating oil ___________________?
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A. Decreases

B. Remains unchanged

C. May increase or decrease; depends on its composition

D. Increases

3904. Stefan-Boltzmann law applies to _____________ body?
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A. Black

B. Any colour

C. Grey

D. White

3905. Terminal point temperature differences between fluids in case of a heat exchanger is termed as__________________?
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A. Log mean temperature difference

B. Approach

C. Geometric mean temperature difference

D. Arithmetic mean temperature difference

3906. Angled baffles are preferred in the agitation tank to control the swirling action; if the viscosity of the liquid to be mixed is about 200 poise. However, the baffle may be completely eliminated for mixing liquids having viscosity above ____________________ poise?
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A. 1000

B. 300

C. 1500

D. 600
3907. The actual temperature drop across the heating surface of an evaporator depends on the_______________?
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A. Liquid depth over the heating surface

B. Solution being evaporated

C. All A., B. and C.

D. Pressure difference between the steam chest and the vapor space above the boiling liquid

3908. 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?
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A. Linear

B. Parabolic

C. Hyperbolic

D. Logarithmic

3909. The driving potential for the crystal growth during crystallisation is the _______________ of the solution?
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A. Density

B. Super-saturation

C. Concentration

D. Viscosity

3910. Loss of heat from untagged steam pipe to the ambient air is by __________________?
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A. Conduction

B. All A., B. & C.

C. Radiation

D. Convection

3911. The film co-efficient between condensing vapour and metal wall increases with _____________________?
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A. Decreasing temperature of the vapour

B. Increasing temperature of the vapour

C. Increasing viscosity of the film of condensate

D. Increasing temperature drop

3912. 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______________________?
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A. 4000

B. 5000

C. 6000

D. 2000

3913. Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter) ?
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A. 0.5 D

B. 0.66 D

C. 0.80 D

D. 0.2 D
3914. (Le/D) for couplings and unions would be_______________?
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A. 60

B. Negligible

C. 200

D. 350

3915. The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu ? 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 _________________?
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A. D1.8

B. D0.2

C. D-0.2

D. D-1.8

3916. Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator ?
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A. Long vertical evaporator

B. Calandria vertical tube evaporator

C. Horizontal tube evaporator

D. Agitated film evaporator
3917. In a shell and tube heat exchanger, the overall heat transfer co-efficient is proportional to the tube side (volumetric flow rate)0.8. This is valid, only when the ratio of the tube side film resistance to the total resistance is almost equal to____________________?
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A. 2

B. 20.8

C. ?

D. 1
3918. Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter)?
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A. 0.2 D

B. 0.80 D

C. 0.66 D

D. 0.5 D

3919. Boiling point elevation for a strong and concentrated solution is found by Duhrings rule, which states that at the same pressure, the boiling point of a solution is a linear function of the _______________ of pure water?
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A. Density

B. Kinematic viscosity

C. Boiling point

D. Dynamic viscosity

3920. Solid angle subtended by the finite surface at the radiating element is_________________?
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A. Expressed in terms of radians

B. Called the view factor

C. Called the angle of vision

D. Proportional to the square of the distance between surfaces