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 247 of 350
- A. 0.06 to 120
- B. 1 to 103
- C. 0.6 to 120
- D. 1 to 50
Explanation: The Colburn analogy is commonly applied for Prandtl numbers from about 0.6 to 120.
Correct answer: 0.6 to 120- A. Thermal conductivity
- B. Thermal diffusivity
- C. Heat transfer co-efficient
- D. Heat flux
Explanation: Heat flux is the heat-transfer rate per unit area, q/A, and is commonly measured in W/m².
Correct answer: Heat flux- A. Sum
- B. Difference
- C. Ratio
- D. None of these
Explanation: Tube pitch is the centre-to-centre spacing between adjacent tubes, equal to the tube outside diameter plus the clear gap between tubes.
Correct answer: Sum- A. Small
- B. All
- C. Large
- D. One fixed
Explanation: An ideal black body emits radiation over the complete wavelength spectrum, although the intensity is not equal at every wavelength.
Correct answer: All- A. Decreases
- B. Remain constant
- C. Increases
- D. First decreases upto certain temperature and then increases
Explanation: In non-metallic amorphous solids, heat is carried mainly by lattice vibrations, and their thermal conductivity generally increases with…
Correct answer: Increases- A. 0.5
- B. 2
- C. 10
- D. 100
Explanation: For conduction from an isolated sphere into a stagnant surrounding medium, the characteristic spherical solution gives Nu = hD/k = 2.
Correct answer: 24927. The main purpose of providing fins on heat transfer surface is to increase the_________________?
- A. Heat transfer area
- B. Mechanical strength of the equipment
- C. Temperature gradient
- D. Heat transfer co-efficient
Explanation: Fins extend the available solid-fluid interface, increasing the heat-transfer area and therefore the total heat-transfer rate.
Correct answer: Heat transfer area- A. Pool
- B. Nucleate
- C. Film
- D. Transition
Explanation: When a stable vapour or gas blanket separates the hot surface from the liquid, the process is called film boiling.
Correct answer: Film- A. 77.2
- B. 71.2
- C. 63.8
- D. 48.7
Explanation: The conduction and convection resistances are 0.2/1.2 and 1/10 m²·K/W, respectively.
Correct answer: 48.7- A. Both A. and B.
- B. Total radiation only
- C. Monochromatic radiation only
- D. Only volumes and not to surfaces
Explanation: Kirchhoff’s law relates emissive power and absorptivity and can be stated for both wavelength-specific radiation and total radiation.
Correct answer: Both A. and B.- A. 16.5 kW/m2
- B. 12.0 kW/m2
- C. 14.6 kW/m2
- D. 11.2 kW/m2
Explanation: For the same furnace temperature, net radiation varies as T_element⁴ − T_furnace⁴, with temperatures in kelvin.
Correct answer: 16.5 kW/m2- A. 125
- B. 133
- C. 150
- D. 160
Explanation: The resistance of layer A is (L_B/2)/(2k_B)=L_B/(4k_B), while that of B is L_B/k_B, so the temperature drops divide in the ratio 1:4.
Correct answer: 160- A. Mainly Gr
- B. Re, Gr
- C. Re, Pr
- D. Re only
Explanation: Forced-convection correlations commonly express Nusselt number as a function of Reynolds and Prandtl numbers, such as Nu = f(Re, Pr).
Correct answer: Re, Pr- A. m°K/W
- B. W/m2°K
- C. m2°K
- D. m2°K/W
Explanation: Fouling factor is a thermal resistance per unit area, since it is added to heat-transfer resistance on an area basis.
Correct answer: m2°K/W4935. In the free convection regime of pool boiling, the heat flux is proportional to__________________?
- A. Δt1/2
- B. Δt5/4
- C. Δt2
- D. Δt
Explanation: In the free-convection region before vigorous nucleate boiling, the pool-boiling heat flux varies approximately as the temperature excess…
Correct answer: Δt5/4- A. CP μ/a
- B. hD/k
- C. CP μ/k
- D. μ/h CP
Explanation: Using thermal diffusivity α = k/(ρCp) and momentum diffusivity ν = μ/ρ gives Pr = ν/α = μCp/k.
Correct answer: CP μ/k- A. Steam
- B. None of these
- C. Non-condensable
- D. Condensate
Explanation: A steam trap automatically discharges condensate and sometimes non-condensable gases while retaining live steam in the line.
Correct answer: Condensate- A. Wien's
- B. Dalton's
- C. Stefan's
- D. Kirchoff's
Explanation: Wien's displacement law states that the wavelength at maximum blackbody emission is inversely proportional to absolute temperature, λmaxT…
Correct answer: Wien's- A. Rate of heat transfer
- B. Heat balance consideration
- C. Both A. and B.
- D. Neither A. nor B.
Explanation: Evaporator economy is determined primarily from the heat and mass balance, especially how the vapour generated in one effect supplies heat…
Correct answer: Heat balance consideration- A. 6
- B. 12
- C. 18
- D. 24
Explanation: For layers in series, temperature drop is proportional to thermal resistance L/k.
Correct answer: 12