chemical engineering MCQs – Page 217

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 Review each marked answer and report any item that may be outdated or unclear.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

4321. If 1.5 moles of oxygen combines with aluminium to form Al2O3, then the weight of aluminium (atomic weight = 27) used in this reaction is __________ gm?
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A. 54

B. 27

C. 5.4

D. 2.7

4322. An equation for calculating vapour pressure is given by, log10 P = A B(t + c). This is called the________________?
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A. Kopps rule

B. Troutons rule

C. Kistyakowsky equation

D. Antoine equation

4323. Pick out the wrong statement pertaining to a shell and tube heat exchanger ?
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A. The maximum value of baffle spacing is equal to the I.D. of the shell

B. The maximum unsupported tube span is generally about 75 times tube diameter, but is reduced to about 60 times for aluminium, copper & alloys of these

C. Disk and doughnut baffle is the most commonly used baffle

D. The minimum value of baffle spacing is 50 mm

4324. A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides __________________?
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A. Higher economy

B. Lower capacity

C. Both A. & B.

D. Lower economy

4325. Spalling of silica bricks occurs due to abrupt volume changes, when it is cooled below a temperature of ______________ C?
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A. 770

B. 270

C. 70

D. 570

4326. Which of the following ideal gas laws are not applicable to mixture of gases ?
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A. Amagats law

B. Daltons law

C. Boyles law & Charles Law

D. None of these

4327. The atomic heat capacities of all solid elements ______________ with decrease in temperature?
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A. Decreases

B. Approach zero at 0C

C. Remains unchanged

D. Increases

4328. Pick out the correct equation ?
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A. jH = (St)2/3(Pr) = f/2

B. jH = (St)(Pr)2/3 = f/2

C. jH = (St)1/3(Pr) = f/2

D. jH = (St)(Pr)1/3 = f/2

4329. The film thickness for laminar film condensation on vertical surface _____________ from top to bottom?
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A. Remain constant

B. Cumulatively decreases

C. Cumulatively increases

D. And the surface conductance increase

4330. Pick out the wrong statement?
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A. Heat sensitive materials should be concentrated in high pressure evaporators

B. Steam jet ejector is used for vapor compression in a thermal recompression evaporator

C. The capacity of an evaporator is reduced by the boiling point elevation

D. Corrosive liquid is normally passed through the tubes in a shell and tube heat exchanger

4331. Steam traps are provided in steam carrying pipelines to_________________?
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A. Condense steam

B. Release excess steam pressure by bleeding steam

C. Remove condensate and inert gases

D. None of these

4332. Ceramic recuperators used for waste heat recovery from high temperature flue gas going out of the furnace is made of ________________?
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A. Siliceous fireclay

B. Silicon carbide

C. Fireclay

D. Corundum

4333. Viscosity of 1 centipoise is equal to 1 Centistoke in case of________________?
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A. None of these

B. Carbon tetrachloride

C. Water

D. Mercury

4334. Which is an acidic refractory ?
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A. Chrome magnesite

B. Fireclay

C. Magnesite

D. Dolomite

4335. For water evaporating into unsaturated air under adiabatic conditions and at constant pressure, the ____________ remains constant throughout the period of vaporisation ?
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A. Dry bulb temperature

B. Humidity

C. Wet bulb temperature

D. Relative saturation

4336. If Prandtl number is greater than the Schmidt number, then the____________________?
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A. Thermal boundary layer lies inside the concentration boundary layer

B. Thermal & concentration boundary layers are of equal thickness

C. Hydrodynamic (i.e., momentum) boundary layer is thicker than the other two

D. Concentration boundary layer lies inside the thermal boundary layer

4337. Pick out the wrong statement?
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A. In a sieve tray, the minimum hole diameter is equal to the tray thickness

B. In practical operation, distillation towers having diameter 3-6 metres equipped with bubble cap (round) size of 15 cms are used

C. In a stainless steel sieve tray, the minimum hole diameter is equal to 10 times the plate thickness

D. Height of packing in a packed tower is about 3 times the column diameter for raschig rings and about 5 to 10 times the column diameter for saddle packing

4338. A vessel of volume 1000 m3 contains air which is saturated with water vapour. The total pressure and temperature are 100 kPa and 20C respectively. Assuming that the vapour pressure of water at 20C is 2.34 kPa, the amount of water vapour (in kg) in the vessel is approximately ?
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A. 17

B. 20

C. 25

D. 34

4339. Presence of MgO in alumino-silicate refractories ______________ its refractoriness ?
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A. Either A. or B.; depends on its quantity

B. Increases

C. Does not affect

D. Lowers

4340. Evaporation of 1kg of water from a solution in a single effect evaporator requires about ________________ kg of steam?
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A. 1-1.3