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 250 of 350
- A. Conduction
- B. Convection
- C. All A., B. & C.
- D. Radiation
Explanation: Heat travels through the pipe wall by conduction, leaves the outer surface by convection to the air, and is also emitted by radiation.
Correct answer: All A., B. & C.4982. In Biot number, the characteristic length used is the ratio of the _______________ of the solid?
- A. Volume to surface area
- B. Perimeter to surface area
- C. Surface area to volume
- D. Surface area to perimeter
Explanation: For a solid of general shape, the characteristic length in the Biot number is V/A, the volume divided by the exposed heat-transfer surface…
Correct answer: Volume to surface area- A. Dynamic viscosity
- B. Boiling point
- C. Kinematic viscosity
- D. Density
Explanation: Duhring's rule states that, at a fixed pressure, the boiling temperature of a solution varies approximately linearly with the boiling…
Correct answer: Boiling point- A. t4
- B. 1/t4
- C. T4
- D. 1/T4
Explanation: The Stefan-Boltzmann law states that blackbody emissive power is proportional to the fourth power of absolute temperature, T⁴.
Correct answer: T4- A. None of these
- B. Reynolds
- C. Prandtl
- D. Colburn
Explanation: The relation St Pr^(2/3) = f/2 is the Colburn heat-and-momentum-transfer analogy.
Correct answer: Colburn- A. 0.5-50
- B. 0.38-0.78
- C. 100-1000
- D. 5-50
Explanation: Most thermal radiation of engineering interest lies roughly in the infrared range, extending approximately from 0.5 to 50 micrometres.
Correct answer: 0.5-50- A. Viscosity
- B. Boiling point (at the same pressure)
- C. Density
- D. Thermal conductivity
Explanation: Duhring's rule states that the boiling point of a solution varies linearly with the boiling point of pure water measured at the same…
Correct answer: Boiling point (at the same pressure)- A. 0.001
- B. 0.72
- C. 70
- D. 150
Explanation: For dry gases, the Prandtl number, Pr = Cpμ/k, is usually close to 0.7 because momentum and thermal diffusivities are of similar…
Correct answer: 0.72- A. Flexibility possible in the baffle arrangement
- B. Less corrosion problems
- C. Low pressure drop
- D. High heat transfer co-efficient
Explanation: The shell side can handle widely varying fluid volumes because baffle spacing and arrangement can be changed to adjust the flow area and…
Correct answer: Flexibility possible in the baffle arrangement- A. Increase the heating load
- B. Account for the uneven expansion of shell and tube bundles
- C. Impart structural strength
- D. Facilitate increase of shell length, if needed
Explanation: Shell and tubes may expand by different amounts when their temperatures differ, producing thermal stress.
Correct answer: Account for the uneven expansion of shell and tube bundles- A. Because of simplicity of fabrication
- B. For low heat load
- C. To obtain higher heat transfer co-efficient and shorter tube
- D. To reduce the pressure drop
Explanation: Multipass arrangements increase fluid velocity, which generally raises the convective heat-transfer coefficient, while allowing the…
Correct answer: To obtain higher heat transfer co-efficient and shorter tube- A. > 0.75
- B. < 0.25
- C. < 0.50
- D. < 0.75
Explanation: The LMTD correction factor accounts for departure from ideal countercurrent flow; a value below about 0.75 indicates an inefficient…
Correct answer: < 0.75- A. Give larger area per tube
- B. Use metal fins of low thermal conductivity
- C. Facilitate very large temperature drop through tube wall
- D. Are used for smaller heat load
Explanation: Fins extend the heat-transfer surface, giving a much larger area for a given tube size, especially when one fluid has a low heat-transfer…
Correct answer: Give larger area per tube- A. Long tube
- B. Falling film
- C. High pressure
- D. None of these
Explanation: A falling-film evaporator provides a short residence time and thin liquid film, limiting thermal damage to heat-sensitive juice.
Correct answer: Falling film- A. D-1.8
- B. D0.2
- C. D-0.2
- D. D1.8
Explanation: Since Nu = hD/k and Nu is proportional to Re^0.8, while Re is proportional to D at fixed velocity and fluid properties, h is proportional…
Correct answer: D-0.2- A. Arithmetic
- B. Either A. or C.
- C. Geometric
- D. Logarithmic
Explanation: For radial conduction through a cylinder, area changes with radius, so the exact resistance contains ln(r2/r1).
Correct answer: Logarithmic- A. Tube diameter
- B. Tube layout
- C. Tube pitch
- D. Number of baffles
Explanation: Shell-side velocity is controlled mainly by the available shell-side flow area, which is changed by tube layout, tube pitch, and baffle…
Correct answer: Tube diameter- A. Parallel
- B. Same in either A , B. or C.
- C. Counter flow
- D. Mixed
Explanation: When one fluid is condensing or evaporating, its temperature remains nearly constant, so the terminal temperature differences and LMTD do…
Correct answer: Same in either A , B. or C.- A. Supersaturated
- B. Wet
- C. Saturated
- D. None of these
Explanation: Saturated steam condenses directly at nearly constant temperature and releases its latent heat efficiently, giving a high film…
Correct answer: Saturated- A. Tar
- B. Coal
- C. Nitrogen
- D. Iron
Explanation: Iron has a much higher thermal conductivity than coal, nitrogen, or tar, allowing heat to pass through it more readily.
Correct answer: Iron