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 243 of 350
- A. Between 0 and ∞
- B. One
- C. ∞
- D. Zero
Explanation: A perfect insulator permits no conductive heat flow, so Fourier’s law requires its thermal conductivity to be zero.
Correct answer: Zero- A. 0.1714 x 10^-8W/m2.°K4
- B. 5.6697 x 10^-8W/m2.°K4
- C. 5.6697 x 10^-8kcal/m2. °K4
- D. 0.1714 x 10^-8kcal/m2. °K4
Explanation: The SI Stefan-Boltzmann constant is σ = 5.6697 × 10⁻⁸ W/m²·K⁴. The kcal-based values are not in the requested SI unit.
Correct answer: 5.6697 x 10^-8W/m2.°K4- A. Plate type
- B. Double pipe type with fin on steam side
- C. Double pipe type with fin on air side
- D. Shell and tube type
Explanation: Air has a much lower convective heat-transfer coefficient than condensing steam, so the air-side resistance controls the exchanger design.
Correct answer: Double pipe type with fin on air side- A. Agitated film evaporator
- B. None of these
- C. Open pan evaporator
- D. Long tube vertical evaporator
Explanation: A long-tube vertical evaporator is commonly used for foaming or frothy liquors because the rising vapor helps carry the liquid upward and…
Correct answer: Long tube vertical evaporator- A. 1000
- B. 727
- C. 800
- D. 1200
Explanation: From q = εσT⁴, T = [22,680/(0.4 × 5.67 × 10⁻⁸)]¹/⁴, which is approximately 1000 K.
Correct answer: 1000- A. Increases rapidly with temperature rise
- B. Decreases rapidly with temperature rise
- C. In independent of pressure
- D. Both B. and C.
Explanation: For an ideal dilute solution, ΔT_b = K_bm, and K_b is approximately proportional to T_b²/ΔH_vap, so the elevation increases as the boiling…
Correct answer: Increases rapidly with temperature rise- A. Facilitate the cleaning of outer tube surface
- B. Hold the tubes in position
- C. Enhance turbulence
- D. All A , B & C
Explanation: Baffles direct the shell-side fluid across the tubes, increasing its velocity and turbulence and therefore improving heat transfer.
Correct answer: Enhance turbulence- A. 5000-15000
- B. 100-500
- C. 1000-1500
- D. 10-50
Explanation: Condensing steam provides a high heat-transfer coefficient, typically about 5000–15000 kcal/(h·m²·°C) in evaporators.
Correct answer: 5000-15000- A. Wavelength of radiation
- B. Temperature of the body
- C. Nature of the body
- D. None of these
Explanation: Kirchhoff’s law gives E/α = Eb, where Eb is the blackbody emissive power at the body’s temperature.
Correct answer: Temperature of the body- A. Δt3
- B. Δt2
- C. Δt
- D. √(Δt)
Explanation: Newton’s law of cooling states that heat-transfer rate is proportional to the excess temperature for small temperature differences: q ∝…
Correct answer: Δt4851. Overall heat transfer co-efficient for cooling of hydrocarbons by water is about_________________?
- A. 50 -100 Kcal/hr.m2.°C
- B. 50 -100 W/m2.°K
- C. 50 -100 BTU/hr. ft.2°F
- D. 1000 - 1500 BTU/hr. ft.2°F
Explanation: Cooling hydrocarbons with water commonly gives an overall coefficient of roughly 50–100 Btu/(h·ft²·°F), because the hydrocarbon-side…
Correct answer: 50 -100 BTU/hr. ft.2°F- A. Horizontal tube
- B. Basket type
- C. Calandria
Explanation: A basket-type evaporator has a removable heating basket, allowing the tubes to be taken out and cleaned intermittently.
Correct answer: Basket type- A. Decreases
- B. Increases
- C. Is not affected
- D. May increase or decrease; depends on the feed
Explanation: Raising the liquor level in a vertical-tube evaporator increases the liquid head and generally weakens circulation, so the overall…
Correct answer: Decreases- A. Increases the heating area required
- B. Reduces the economy
- C. Both A. and B.
- D. Decreases the heating area required
Explanation: A colder feed requires more sensible heating before evaporation, increasing the required heating area and consuming more steam per unit of…
Correct answer: Both A. and B.- A. Baffle spacing & shell diameter
- B. Tube diameter & pitch
- C. Viscosity, density & mass velocity of shell side fluid
- D. None of these
Explanation: Shell-side pressure drop depends on baffle geometry, tube layout, and fluid properties such as viscosity, density, and mass velocity.
Correct answer: None of these- A. Oily
- B. Coated
- C. Glazed & polished
- D. Smooth
Explanation: Dropwise condensation is promoted by a non-wetting surface, and an oily surface helps condensate form separate droplets rather than a…
Correct answer: Oily- A. K/h0
- B. 2K/h0
- C. h0/K
- D. h0/2K
Explanation: For a sphere, balancing the insulation's added conduction resistance against the increased outer area gives the critical radius, r_c =…
Correct answer: 2K/h0- A. There is no internal heat generation
- B. Boundary surfaces are isothermal
- C. Material is anisotropic
- D. Constant temperature gradient exists
Explanation: The usual one-dimensional Fourier-conduction model assumes an isotropic material, so thermal conductivity is not direction-dependent.
Correct answer: Material is anisotropic- A. None of these
- B. Decreasing temperature
- C. Decreasing Reynolds number
- D. Increasing temperature
Explanation: For most liquids, increasing temperature lowers viscosity, which raises the Reynolds number and usually increases the convective…
Correct answer: Increasing temperature- A. Grashoff number
- B. Eckert number
- C. Graetz number
- D. Bond number
Explanation: Natural convection is driven by buoyancy produced by density differences, and the Grashof number compares buoyancy forces with viscous…
Correct answer: Grashoff number