chemical engineering MCQs – Page 88

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 Review each marked answer and report any item that may be outdated or unclear.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

1741. Steam distillation is used to__________________?
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A. Avoid thermal decomposition of a component

B. Reduce the number of plates

C. Increase the total pressure of distillation

D. Increase the efficiency of separation

1742. Blowdown in a cooling tower__________________?
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A. Is undesirable

B. All A., B. & C.

C. Means discarding a small fraction of circulating water to prevent and limit the concentration

D. salt and impurities</strong>

E. Increases the scale forming tendencies of water

1743. Which of the following is not fixed by the process requirements, in the design of absorbers ?
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A. Terminal concentrations of gas stream

B. None of these

C. Flow rate of the entering gas

D. Composition of the entering liquid

1744. Lurgi coal gasifier is a pressurised _______________ bed reactor ?
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A. Fluidised

B. Entrained

C. Moving

D. Fixed

1745. Raschig ring made of porcelain cannot be used for treating concentrated___________________?
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A. Nitric acid

B. Alkalis

C. Hydrochloric acid

D. Sulphuric acid

1746. Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout).For 98% recovery of acetone, the number of trays required is/are ?
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A. 4

B. 10

C. 8

D. 9

1747. Absorption accompanied by heat evolution results in____________________?
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A. None of these

B. Increase in equilibrium solubility

C. Decrease in equilibrium solubility

D. Increased capacity of the absorber

1748. The binary diffusivity in gases and liquids vary respectively as_________________?
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A. T3/2 and ?T

B. ?T and T3/2

C. T3/2 and T

D. T and T3/2

1749. Azeotropism for ethyl alcohol-water system disappears by_____________________?
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A. Decreasing pressure

B. Increasing pressure

C. Increasing temperature

D. No means

1750. The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m2/m3) ?
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A. 500

B. 900

C. 1200

D. 800

1751. Dorr thickener is an equipment used for___________________?
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A. Classification

B. Clarification

C. Leaching

D. Sedimentation

1752. Pick out the wrong statement ?
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A. Acid resistant cements are known as silicate cement

B. High early strength cement are made from materials having high silica to lime ratio

C. Major component of greyish Portland cement is tricalcium silicate

D. The function of gypsum in cement is to enhance its initial setting rate

1753. The equipment used in the extraction of highly corrosive radioactive liquids is_______________________?
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A. Spray column

B. Baffle tower

C. Mixer settler

D. Pulse column

1754. Pick out the wrong statement ?
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A. Mechanical agitation is required, if the system has low interfacial tension

B. Sieve tray towers are generally used for systems having low interfacial tension

C. When Henrys law constant is very small, then the mass transfer rate is controlled by the gas

D. m resistance

E. Taylor-Prandtl analogy for heat and mass transfer considers the transfer through both laminar

F. turbulent layers

1755. For a fixed number of ideal stages in a distillation column, as the reflux ratio is increased, the difference in composition between the top and bottom product streams__________________?
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A. Decreases

B. Increases

C. Remain unaffected

D. Passes through a maximum

1756. All moisture in a non-hygroscopic material is the ________________ moisture?
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A. Unbound

B. Bound

C. Equilibrium

D. Free

1757. The relation among various mass transfer co-efficients (M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C. for equimolar counter diffusion with concentration & mole fraction respectively as the driving force. and, Kp= M.T.C. for diffusion of a gas through a stagnant inert gas with pressure as driving force) ?
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A. Kc = Kp/RT = Km . RT/P

B. Kc = Kp = Km

C. Kc = Kp . RT = Km . RT/p

D. None of these

1758. In stripping section of continuous distillation column, the_______________________?
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A. Vapour is stripped of low boiler

B. Liquid is stripped of high boiler

C. None of these

D. Liquid is enriched with high boiler

1759. Steam distillation is not recommended to be used, if the _____________________?
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A. ponents associated with it, at the boiling temperature

B. Material to be distilled is thermally unstable or has the tendency to react with other

C. ling temperature

D. Liquids decompose, if distilled directly at atmospheric pressure

E. Azeotropic mixture is to be separated and the final product is miscible with water

F. Material cannot be distilled by indirect heating even under low pressure, because of the high

1760. In a distillation column, with increase in the reflux ratio, the heat removed in the cooler ______________________?
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A. Decreases

B. Remains unaffected

C. And the heat required in reboiler decreases

D. Increases

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