chemical engineering MCQs – Page 25

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 Review each marked answer and report any item that may be outdated or unclear.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

481. The refrigerant freon-12 is chemically_______________________?
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A. CClF3

B. CCl4F

C. CCl3F

D. CCl2F2

482. Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of ?
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A. Grashoff number & Reynolds number

B. Grashoff number

C. Reynolds number

D. Grashoff number & Prandtl number

483. The difference between gross & net calorific values of fuel is due to the___________________?
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A. Heat lost by radiation

B. Heat carried away by steam from the combustion of hydrogen in the fuel

C. Sensible heat carried away by the flue gases

D. Heat carried away by the steam from the moisture content of the fuel

484. Which of the following is a boiler accessory i.e., not a boiler mounting ?
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A. Feed water pump

B. Blow off cock

C. Stop valve

D. Feed check valve

485. Aluminium is extracted from____________________?
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A. Bauxite

B. None of these

C. Chalcocite

D. Galena

486. __________________ stress cannot be sustained by a fluid in equilibrium ?
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A. Shear

B. Compressive

C. Tensile

D. None of these

487. Which of the following is not an ore of copper ?
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A. Azurite

B. Chalcopyrite

C. Cryolite

D. Malachite

488. Super conduction in metals is observed at a temperature of ________________ K?
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A. About 273

B. >100

C. <100

D. About 373

489. Cobalt 60 is used as a source of _____________ in medical therapy & industrial radiography?
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A. ?-rays

B. ?-rays

C. X-rays

D. ?-rays

490. Cold chisel & hammers are made of_________________?
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A. Mild steel

B. High speed steel

C. Forged steel

D. High carbon steel

491. Hollow shafts can be made as strong as solid shafts by making the twisting moments of both the shafts same. Shafts made by _____________ have residual stresses ?
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A. Forging

B. Cold rolling

C. Casting

D. Hot rolling

492. The product of a commercial direct reduction process is___________________?
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A. Sponge iron

B. Solid iron

C. Iron saturated with carbon

D. Liquid iron

493. More than 95% of _______________ is present in corundum ?
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A. SiO2

B. CaSiO2

C. Al2O3

D. MgO

494. Most important property of steels for use in automobile bodies is the___________________?
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A. Toughness

B. Resilience

C. Yield strength

D. Formability

495. Density in the solid state is slightly less than that in its liquid state, in case of____________________?
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A. Water

B. None of these

C. Mercury

D. Carbon dioxide

496. Pick out the wrong statement ?
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A. Recrystallisation temperature decreases with decrease in strain in a cold worked metal

B. Lead can creep under its own weight at room temperature

C. The electrical conductivity of gold is considerably reduced by alloying additions due to the

D. rease in electron movement

E. With increase in temperature, the electrical conductivity of intrinsic semi-conductor will

497. Projection welding & stud welding is categorised as the _______________ welding?
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A. Thermit

B. Pressure

C. Arc

D. Resistance

498. Which of the following heat treatment processes is usually applied to castings ?
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A. Annealing

B. Normalising

C. Carburising

D. Tempering

499. What is the critical radius of insulation (cms) for a metallic cylinder, if the convective heat transfer co-efficient with the ambient atmosphere is 5 W/m2. K? Thermal conductivity of metal and insulation material are 40 and 0.1 W/m.K respectively ?
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A. 2

B. 40

C. 10

D. 8

500. In a counter flow heat exchanger, hot fluid enters at 170C & leaves at 150C, while the cold fluid enters at 50C & leaves at 70C. The arithmetic mean temperature difference in this case is ______________ C?
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A. 120

B. 20

C. ?

D. 60

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