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 241 of 350
- A. d2T/dZ2 > 0
- B. d2T/dZ2 = 0
- C. d2T/dZ2 < 0
- D. dT/dZ = 0
Explanation: The endpoint temperature differences are 80 - 60 = 20°C and 50 - 30 = 20°C, so the temperature difference remains constant along the…
Correct answer: d2T/dZ2 = 0- A. Resistances in parallel
- B. Capacitors in series
- C. Resistances in series
- D. None of these
Explanation: In steady heat conduction, the same heat flux passes through each resistance in series, just as the same electric current passes through…
Correct answer: Resistances in series- A. High viscosity
- B. Low temperature gradients
- C. High co-efficient of thermal expansion
- D. Low density change with temperature
Explanation: Natural convection is strengthened by a large coefficient of thermal expansion because a given temperature difference produces a larger…
Correct answer: High co-efficient of thermal expansion- A. St = f1/2
- B. St = f/4
- C. St = 4f
- D. St = f/2
Explanation: Reynolds analogy equates heat and momentum transfer as St = f/2 when f denotes the Fanning friction factor.
Correct answer: St = f/2- A. The heat transfer rate is low in view of the large temperature drop
- B. It is difficult to maintain
- C. It is not economic
- D. None of these
Explanation: Film boiling creates a vapour film that acts as an insulating layer between the heating surface and liquid.
Correct answer: The heat transfer rate is low in view of the large temperature drop- A. Heat sensitive material can be handled
- B. Most concentrated liquid is at highest temperature
- C. There is no additional cost of pumping
- D. Equal heat transfer co-efficients exist in various effects
Explanation: In backward feed, the most concentrated and viscous liquid is heated in the last effect, where the temperature is highest.
Correct answer: Most concentrated liquid is at highest temperature- A. Does not affect
- B. Decreases
- C. Increases
- D. May increase or decrease, depends on the type of baffle
Explanation: Shell-side baffles force the fluid across the tubes instead of allowing it to flow mainly parallel to them.
Correct answer: Increases4808. Electromagnetic radiations propagate in vacuum with a velocity of _______________ metre/second?
- A. 3 x 10^5
- B. 3 x 10^12
- C. 3 x 10^10
- D. 3 x 10^8
Explanation: Electromagnetic radiation travels through vacuum at the speed of light, approximately 3 × 10^8 m/s.
Correct answer: 3 x 10^8- A. Facilitate cleaning of the exchanger
- B. Relieve stresses caused by thermal expansion
- C. Increase the heat transfer area
- D. Increase log mean temperature gradient
Explanation: A floating head allows one tube-sheet assembly to move relative to the shell.
Correct answer: Relieve stresses caused by thermal expansion- A. Bleed point
- B. Vent
- C. Catchall
- D. Baffle
Explanation: A catchall or entrainment separator is installed in the vapour line to intercept liquid droplets carried over with the vapour.
Correct answer: Catchall- A. Not related with
- B. Greater than
- C. Equal to
- D. Smaller than
Explanation: The pressure-drop equivalent diameter uses the full wetted perimeter, whereas the heat-transfer equivalent diameter uses only the heated…
Correct answer: Smaller than- A. Accounts for additional resistances to heat flow
- B. Does not provide a safety factor for design
- C. Is a dimensionless quantity
- D. None of these
Explanation: A fouling factor represents the added thermal resistance caused by deposits such as scale, corrosion products, or biological films.
Correct answer: Accounts for additional resistances to heat flow- A. Remains unchanged
- B. Decreases
- C. Increases or decreases depending on number of shell passes
- D. Increases
Explanation: Increasing baffle spacing enlarges the shell-side flow area, so shell-side mass velocity and fluid velocity fall.
Correct answer: Decreases- A. J/M2°K
- B. W/m°K
- C. W/m2°K
- D. J/m°K
Explanation: The heat-transfer coefficient relates heat flux to temperature difference, so its SI unit is power per area per temperature difference…
Correct answer: W/m2°K- A. Series and parallel set of shell and tube
- B. Plate fine
- C. Double pipe
- D. None of these
Explanation: Shell-and-tube exchangers can be arranged in series and parallel to provide a very large heat-transfer area and handle high heat duties.
Correct answer: Series and parallel set of shell and tube- A. Increases
- B. Decreases
- C. Remains unchanged
- D. May increase or decrease; depends on the solid
Explanation: Increasing porosity replaces more of the solid conducting path with gas-filled voids, and gases generally conduct heat much less…
Correct answer: Decreases- A. Capacity
- B. Rate of evaporation
- C. Economy
- D. Rate of vaporisation
Explanation: Economy is defined as the kilograms of solvent vapour produced per kilogram of steam consumed.
Correct answer: Economy- A. Laminar
- B. Transition
- C. Both A & B
- D. Highly turbulent
Explanation: In highly turbulent flow, mixing rapidly eliminates entrance-region effects, so the heat-transfer coefficient is essentially independent…
Correct answer: Highly turbulent- A. Reynolds number
- B. Prandtl number
- C. None of these
- D. Grashoff number
Explanation: Forced convection is governed mainly by Reynolds and Prandtl numbers, which represent flow regime and momentum-to-thermal diffusivity…
Correct answer: Grashoff number- A. C/E
- B. E/C
- C. CE
- D. 1/CE
Explanation: Economy equals evaporation rate divided by steam consumption, so rearranging gives steam consumption = capacity/economy.
Correct answer: C/E