chemical engineering MCQs – Page 210

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 Review each marked answer and report any item that may be outdated or unclear.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
4181. For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally ?
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A. Remains unchanged

B. Decreases

C. Increases exponentially

D. Increases

4182. 200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 10-3 kg/m2.s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m2/1000 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid)?
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A. 0.05

B. 0.15

C. 0.5

D. 0.1
4183. _____________ equation relates the thermal conductivity of a solid to its temperature ?
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A. Kistyakowsky

B. 217;s

C. Lees

D. Antoine

4184. A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300C and allowed to cool in natural air. Which one will cool the slowest ?
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A. All will cool at the same rate

B. Plate

C. Cube

D. Sphere
4185. Thermal conductivity of a gas at low density, ___________ with increase in temperature ?
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A. Increases

B. May increase or decrease; depends on the gas

C. Decreases

D. Remains unchanged

4186. The critical radius r of insulation on a pipe is given by____________________?
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A. r = h/k

B. r = 2k/h

C. r = k/2h

D. r = k/h
4187. Overall heat transfer co-efficient for cooling of hydrocarbons by water is about_________________?
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A. 50 -100 W/m2.K

B. 1000 1500 BTU/hr. ft.2F

C. 50 -100 Kcal/hr.m2.C

D. 50 -100 BTU/hr. ft.2F
4188. Which of the following is not concerned with the heat transfer ?
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A. Peclet number

B. Stanton number

C. Brinkman number

D. Schmidt number
4189. Radiation heat losses from satisfactorily insulated high pressure boiler may be about _____________ percent?
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A. 7

B. 26

C. 18

D. 1

4190. 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?
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A. None of these

B. Vacuum

C. Backward feed

D. High pressure

4191. Heat transfer by ____________ may not necessarily require the presence of a medium?
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A. Forced convection

B. Radiation

C. Conduction

D. Natural convection

4192. 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 ________________?
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A. Remain unchanged

B. Increase by 216

C. Increase by 1.8 times

D. Decrease by 22

4193. Colburn analogy is applicable for the value of Prandtl number from_________________?
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A. 0.6 to 120

B. 0.001 to 1

C. 0.5 to 5

D. 120 to 400

4194. Small scale evaporation is done in a_________________?
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A. Condenser

B. Heat exchanger

C. Multiple effect evaporator

D. Steam jacketed kettle
4195. In case of evaporators, liquid entrainment results primarily due to_________________?
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A. Foaming of the solution

B. High evaporation rate

C. High vacuum in the evaporator

D. High heat transfer rate

4196. Which of the following has the minimum thermal conductivity ?
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A. Carbon black

B. Nitrogen

C. Tar

D. Steel

4197. In SI units, fouling factor is expressed in __________________?
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A. W/m2K

B. m2K

C. mK/W

D. m2K/W
4198. Thermal conductivity of a conducting solid material depends upon its_______________?
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A. Temperature

B. Porosity

C. Both A. & B.

D. Neither A. nor B.

4199. In a cooling tower, water becomes cool by________________?
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A. Loosing sensible heat

B. Loosing latent heat

C. Vaporisation due to heat loss to air

D. Heat transfer to surroundings

4200. For a multipass shell and tube heat exchanger, the LMTD correction factor is always________________?
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A. < 1

B. 1

C. > 1

D. Between 1 & 2