chemical engineering MCQs – Page 202

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 Review each marked answer and report any item that may be outdated or unclear.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

4021. Tube pitch is the _______________ of tube diameters and the clearances?
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A. Ratio

B. Difference

C. Sum

D. None of these

4022. The value of Stefan-Boltzmann constant in SI unit is_________________?
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A. 5.6697 10-8W/m2.K4

B. 0.1714 10-8W/m2.K4

C. 0.1714 10-8kcal/m2. K4

D. 5.6697 10-8kcal/m2. K4

4023. A long iron rod initially at a temperature of 20C has one end dipped in boiling water (100C) 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 40C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time ___________________?
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A. t = 400 s

B. t = 800 s

C. t = 283 s

D. t = 356 s

4024. With increase in porosity, the thermal conductivity of a solid substance__________________?
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A. May increase or decrease; depends on the solid

B. Increases

C. Remains unchanged

D. Decreases

4025. Which of the following accessories is provided in the vapor line of an evaporator for removing the entrained liquid ?
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A. Catchall

B. Baffle

C. Bleed point

D. Vent

4026. Dropwise condensation occurs on ______________ surfaces?
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A. Smooth clean

B. Contaminated cooling

C. Polished

D. Clean and dirt free

4027. Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is ________________ law?
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A. Kirchoffs

B. Wiens

C. Daltons

D. Stefans

4028. In counter flow compared to parallel flow, ?
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A. LMTD is greater

B. Less surface area is required for a given heat transfer rate

C. Both A. and B.

D. More surface area is required for a given heat transfer rate

4029. Air is best heated with steam in a heat exchanger of__________________?
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A. Shell and tube type

B. Plate type

C. Double pipe type with fin on steam side

D. Double pipe type with fin on air side

4030. The sum of reflectivity and absorptivity for an opaque body is equal to____________________?
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A. 0.5

B. 0

C. 1

D. 2

4031. Value of Prandtl number for water ranges from_________________?
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A. 1000 to 2000

B. 100 to 500

C. 1 to 2

D. 5 to 10

4032. 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_____________?
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A. Horizontal heat exchanger with steam on shell side

B. Horizontal heat exchanger with steam on tube side

C. Vertical heat exchanger with steam on tube side

D. Vertical heat exchanger with steam on shell side

4033. The most conducive surface for dropwise condensation to occur is the _____________ surface?
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A. Smooth

B. Oily

C. Glazed & polished

D. Coated

4034. Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is________________?
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A. Finned tube heat exchanger with air inside and steam outside

B. Shell and tube heat exchanger with air inside tubes and steam on shell side

C. Finned tube heat exchanger with air outside and steam inside

D. Shell and tube heat exchanger with air on shell side and steam inside tubes

4035. Choose the most important factor on which the heat conducted through a wall in a unit time will depend on ?
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A. Area of the wall perpendicular to heat flow

B. Thickness of the wall

C. Material of the wall

D. Temperature difference between the two surfaces of the wall

4036. Out of the following four assumptions used in the derivation of the equation for LMTD [LMTD = (?t1 ?t2)/ln(?t1/?t2)], which one is subject to the largest deviation in practice ?
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A. No partial phase change in the system

B. Constant rate of fluid flow

C. Constant specific heat

D. Constant overall heat transfer co-efficient.

4037. Kg of liquid evaporated per hour in an evaporator is defined as its_________________?
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A. None of these

B. Economy

C. Steam load

D. Capacity

4038. A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun ?
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A. Yellow paint

B. White paint

C. Black paint

D. Grey paint

4039. A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an___________________?
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A. Ellipse

B. Parabola

C. Straight line

D. Circular arc

4040. Value of Nusselt number [Nu = (hD/k)] for the heat transfer by conduction from a droplet or a spherical particle to a surrounding stagnant film is__________________?
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A. 2

B. 100

C. 0.5

D. 10

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