All Free Chemical Engineering MCQs with Answers
Every Chemical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
6,983 questions · page 237 of 350
- A. 15 min
- B. 22 min
- C. 44 min
- D. 51 min
Explanation: For batch heating with condensing steam at constant temperature, t = (mCp/UA) ln[(150−30)/(150−120)] = 3080 s, or about 51 minutes.
Correct answer: 51 min- A. Cannot pass through vacuum
- B. Travel in straight line
- C. Both B. and C.
- D. Can be reflected by a mirror
Explanation: Heat waves are electromagnetic radiation, so they can travel through a vacuum, propagate in straight lines, and undergo reflection from…
Correct answer: Both B. and C.- A. Increase
- B. Not affect
- C. Decrease
- D. Increase the condensing film co-efficient as well as
Explanation: Air adds a diffusion resistance between the condensing vapor and the cooling surface, reducing the effective condensation rate.
Correct answer: Decrease- A. > 10000
- B. 4000
Explanation: This correlation is the Dittus-Boelter equation, which applies to fully developed turbulent flow in a smooth pipe, normally for Reynolds…
Correct answer: > 10000- A. Peclet
- B. Prandtl
- C. Stanton
- D. Nusselt
Explanation: The ratio of momentum diffusivity to thermal diffusivity is the Prandtl number, Pr = ν/α.
Correct answer: Prandtl4726. Vibrations in the tubes of a shell and tube heat exchanger is induced due to the _________________?
- A. Flow of fluid on the tube and shell sides
- B. Oscillations in the flow of shell/tube sides fluid
- C. All A., B. and C.
- D. Vibrations transmitted through piping and/or supports due to external reasons
Explanation: Tube vibration can arise from fluid-flow excitation on either side, oscillatory flow, or vibration transmitted from external piping and…
Correct answer: All A., B. and C.- A. 1
- B. > 1
- C. 0.1
- D. < 1
Explanation: In a single-effect evaporator, the steam economy is generally less than 1 because one kilogram of steam evaporates less than one kilogram…
Correct answer: < 1- A. 1
- B. 1.74
- C. 6.1
- D. 37
Explanation: With constant properties and doubled volumetric flow, halving the diameter makes velocity increase eightfold, so Reynolds number increases…
Correct answer: 6.1- A. Increase the cross-section of the shell side liquid
- B. Increase the shell side heat transfer co-efficient
- C. Force the liquid to flow parallel to the bank
- D. Decrease the shell side heat transfer co-efficient
Explanation: Baffles redirect shell-side fluid across the tube bundle rather than allowing mainly parallel flow, increasing turbulence and the…
Correct answer: Increase the shell side heat transfer co-efficient- A. No
- B. The least
- C. Lower
- D. The largest
Explanation: The overall resistance is dominated by the largest individual resistance because resistances act in series.
Correct answer: The largest- A. Lewis relationship
- B. Nusselt number
- C. Kutateladze number
- D. Froude number
Explanation: The Lewis relationship connects simultaneous heat and mass transfer, especially in gas-liquid contacting, by relating heat-transfer and…
Correct answer: Lewis relationship- A. Distillation
- B. Evaporation
- C. Crystallisation
- D. Humidification
Explanation: Dühring's rule states that the boiling point of a solution varies approximately linearly with the boiling point of the pure solvent at the…
Correct answer: Evaporation- A. T1 - T2
- B. T1 - Ta
- C. None of these
- D. T2 - Ta
Explanation: Radiative heat exchange depends on the fourth powers of absolute temperatures, such as T₁⁴ − T₂⁴, rather than on any simple temperature…
Correct answer: None of these- A. And the surface conductance increase
- B. Cumulatively decreases
- C. Remain constant
- D. Cumulatively increases
Explanation: Condensate formed at the top flows downward and joins the condensate already present, so the laminar film becomes cumulatively thicker…
Correct answer: Cumulatively increases- A. White lead
- B. Black
- C. Grey
- D. Light cream
Explanation: White lead reflects most incident radiation, giving it a very low absorption coefficient compared with black, grey, or light-coloured…
Correct answer: White lead- A. Radiation
- B. Natural convection
- C. Forced convection
- D. Conduction
Explanation: Forced convection occurs when fluid motion is produced by an external device or pressure change, such as a pump, fan, or compressor.
Correct answer: Forced convection- A. Total
- B. Monochromatic
- C. Neither A. nor B.
- D. Both A. & B.
Explanation: Kirchhoff’s radiation law relates emissive power and absorptivity for both total radiation and radiation at a specified wavelength, called…
Correct answer: Both A. & B.- A. Zero
- B. Maximum
- C. Minimum
- D. Infinity
Explanation: For parallel flow, equal hot- and cold-stream outlet temperatures make the terminal temperature difference zero.
Correct answer: Zero- A. Mainly confined to a thin film of fluid near the surface
- B. Uniformly distributed throughout the fluid
- C. In the central core of the fluid
- D. None of these
Explanation: Near a solid-fluid interface, the fluid velocity falls to zero and a strong temperature gradient develops across a thin boundary film.
Correct answer: Mainly confined to a thin film of fluid near the surface- A. Concentration boundary layer lies inside the thermal boundary layer
- B. Thermal boundary layer lies inside the concentration boundary layer
- C. Thermal & concentration boundary layers are of equal thickness
- D. Hydrodynamic (i.e., momentum) boundary layer is thicker than the other two
Explanation: Prandtl number compares momentum diffusivity with thermal diffusivity, while Schmidt number compares momentum diffusivity with mass…
Correct answer: Thermal boundary layer lies inside the concentration boundary layer