chemical engineering MCQs – Page 283

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 Review each marked answer and report any item that may be outdated or unclear.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
5641. High temperature in gasification of coal favours________________?
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A. High production of CO2

B. Low production of CO2

C. High production of CO

D. Both B. and C.
5642. Presence of free moisture in coal during its high temperature carbonisation _____________________?
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A. Protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot

B. Reduces the coking time

C. n walls</strong>

D. Increases the loss of fine coal dust from the ovens when charging

E. None of these

5643. Pick out the wrong statement?
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A. Crimp is a measure of the difference between the length of the straightened and unstraightened fibre

B. Nylon fibres have greater water absorption capacity than polyester fibres

C. Dacron fibres, acrylic fibres, viscose rayon fibres & cellulose acetate fibres are all prepared by wet spinning

D. Denier is defined as weight in gm of 9000 metres length of a fibre, while tex is defined as weight in gm of 1000 metres length of fibre

5644. The calorific value of a gas of composition CO2 = 20%, H2 = 50%, CH4 = 30%, is y. If the composition of gas is changed to H2 = 50%, CH4 = 30%, CO2 = 10%, N2 = 10%, then the calorific value will be___________________?
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A. 1.05 y

B. y

C. 0.95 y

D. 1.8 y

5645. The maximum adiabatic flame temperature is attained, when the fuel is burnt with ______________________?
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A. Theoretically required amount of air

B. More than theoretically required amount of air

C. Less than theoretically required amount of air

D. Theoretically required amount of oxygen
5646. Which of the following is unsuitable fuel for producer gas manufacture ?
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A. Coal having low fusion point of its ash

B. Coke

C. Coal having high fusion point of its ash

D. Anthracite

5647. Calorific value of coke even gas produced by low temperature carbonisation of coal is about ____________ Kcal/Nm3?
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A. 2500

B. 10000

C. 4000

D. 6500
5648. Low temperature oxidation and spontaneous combustion of freshly mined coal is accentuated, if __________________?
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A. Smaller fines are stored in large quantity

B. It is stored in tall heaps

C. It contains large amount of volatile matter

D. All A., B. and C.
5649. Which of the following is not a manufactured fuel ?
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A. Coke breeze

B. Charcoal

C. Soft coke

D. Colloidal fuels

5650. As the equilibrium moisture content of the coal increases, its___________________?
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A. Swelling number decreases

B. Swelling number increases

C. Calorific value increases

D. Bulk density decreases

5651. The temperature at which plastic layer formation takes place during carbonisation of coal varies from ______________ C ?
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A. 700 to 850

B. 100 to 150

C. 350 to 450

D. 550 to 650

5652. Which of the following is not increased by using preheated combustion air in place of ordinary air at room temperature ?
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A. Flame temperature achieved

B. Heat transfer rate to the stock in the furnace

C. Speed of combustion of fuel

D. Calorific value of the fuel
5653. Gobar gas is produced by the _______________ of gobar (cow dung) ?
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A. Oxidation

B. Hydrolysis

C. Fermentation

D. Dehydration

5654. Fischer-Tropsch method aims at the ______________________?
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A. None of these

B. Hydrogenation of coal to produce gasoline

C. Synthesis of gasoline (from water gas)

D. Gasification of coal

5655. Caking coal is desirable for_________________?
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A. Coke making

B. Burning on travelling grate

C. Burning on firebars

D. All A., B. and C.

5656. The maximum adiabatic flame temperature in air as compared to that in pure oxygen is_______________?
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A. Same

B. Much higher

C. Either lower or higher, depends on the type of fuel

D. Much lower
5657. Yield of charcoal in high temperature carbonisation of wood is about _____________ percent?
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A. 75

B. 25

C. 50

D. 10

5658. Gross heating value of coal is ______________ the net heating value?
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A. Higher than

B. Same as

C. Lower than

D. None of these

5659. Which of the following combustibles is absent in blast furnace gas ?
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A. CO

B. None of these

C. CH4

D. H2

5660. The maximum percentage of CO2 in a flue gas (from a carbonaceous fuel) can be_________________?
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A. 21

B. 29

C. 77

D. 79