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 275 of 350
- A. Flow rate of liquid
- B. Flow rate of gas
- C. Type and size of packing
- D. None of these
Explanation: HETP is influenced by liquid and gas flow rates as well as packing type and size because these affect wetting, interfacial area, and…
Correct answer: None of these- A. Wet bulb temperature
- B. Dew point
- C. Dry bulb temperature
- D. None of these
Explanation: Adiabatic saturation occurs at essentially constant wet-bulb temperature because sensible cooling of the air supplies the latent heat for…
Correct answer: Wet bulb temperature- A. Heat gain or loss
- B. Flow rate of entering liquid
- C. Flow rate of gas
- D. None of these
Explanation: The entering gas rate and heat effects are normally specified as design conditions, whereas the liquid rate can be selected from the…
Correct answer: Flow rate of entering liquid- A. Equilibrium
- B. Critical
- C. Unbound
- D. Bound
Explanation: Unbound moisture is held by surface forces weakly and can be removed relatively easily by evaporation.
Correct answer: Unbound- A. Of high viscosity to give high tray efficiency
- B. Of high volatility
- C. Present in overhead stream
- D. Added to alter the relative volatility of the mixture
Explanation: The solvent in extractive distillation is added to change the relative volatility of the components, allowing difficult separations.
Correct answer: Added to alter the relative volatility of the mixture- A. Partial pressure of vapour in the mixture
- B. Heat capacity of the vapour
- C. Density of the vapour
- D. None of these
Explanation: At fixed total pressure, humidity is determined by the partial pressure of water vapour in the gas mixture.
Correct answer: Partial pressure of vapour in the mixture- A. 1
- B. 0.5
- C. 10
- D. 0
Explanation: Equal mass, thermal, and momentum diffusivities mean that mass diffusivity, thermal diffusivity, and eddy momentum diffusivity have equal…
Correct answer: 1- A. D ∝ T
- B. D ∝ T0.5
- C. D ∝ T2
- D. D ∝ T1.5
Explanation: For binary gas diffusion at approximately constant pressure, diffusivity follows the Chapman-Enskog relationship and varies roughly as…
Correct answer: D ∝ T1.5- A. Integral heat of adsorption
- B. Heat of wetting
- C. Differential heat of adsorption
- D. Heat of normal condensation
Explanation: The integral heat of adsorption is the enthalpy change per unit mass of adsorbate for loading an initially outgassed adsorbent from zero…
Correct answer: Integral heat of adsorption- A. Binary
- B. Constant boiling point
- C. Ternary
- D. None of these
Explanation: An azeotrope boils at a constant temperature because its vapour and liquid compositions are identical at the azeotropic point.
Correct answer: Constant boiling point- A. Highest temperatures is near the feed plate
- B. Driving force for the liquid flow is its weight
- C. Vapors are not always at their dew points
- D. All A., B. and C.
Explanation: Liquid flows down a distillation column mainly because of gravity, so its driving force is its weight.
Correct answer: Driving force for the liquid flow is its weight- A. Reboiler load
- B. Condenser load
- C. Number of plates
- D. All A., B. and C.
Explanation: At total reflux, all condensed overhead liquid is returned to the column and no products are withdrawn, producing the maximum reflux ratio…
Correct answer: Number of plates- A. Pressure
- B. Humidity
- C. Temperature
- D. Both B. and C.
Explanation: A boiling-point diagram is based on vapour-liquid equilibrium at a specified pressure and composition, so ambient pressure can affect it.
Correct answer: Both B. and C.- A. 21.7
- B. 20
- C. 27.3
- D. 18.7
Explanation: At the original dew point, benzene's partial pressure is approximately its saturation pressure at 20°C, or 75 mm Hg.
Correct answer: 18.7- A. Same as "Van der Waals" adsorption
- B. Characterised by adsorption of heat
- C. An irreversible phenomenon
- D. A reversible phenomenon
Explanation: Chemisorption involves chemical-bond formation between the adsorbate and surface, so it generally has a high heat of adsorption and is…
Correct answer: An irreversible phenomenon- A. LG/m
- B. G/mL
- C. mL/G
- D. L/mG
Explanation: The absorption factor compares the liquid carrying capacity with the gas-phase resistance and is defined as A = L/(mG).
Correct answer: L/mG- A. Infinity
- B. Unity
- C. Zero
- D. None of these
Explanation: For a saturated-liquid feed, q = 1, and the q-line slope q/(q - 1) becomes infinite.
Correct answer: Infinity- A. Constant molal overflow
- B. All A., B. and C.
- C. Constant relative volatility
- D. Total reflux
Explanation: The Fenske relation gives the minimum number of stages at total reflux and is commonly applied with constant relative volatility and…
Correct answer: All A., B. and C.- A. Slope of the operating line in stripping section decreases
- B. Number of plates decreases very slowly first and then more and more rapidly
- C. Total cost first decreases and then increases
- D. Liquid flow increases while the vapor flow decreases for a system
Explanation: Increasing reflux reduces the number of stages required, but it increases internal flows and operating cost.
Correct answer: Total cost first decreases and then increases- A. Have low weight per unit volume
- B. Have large surface area per unit volume
- C. Have large free cross-section
- D. Hold up large amount of liquid in the packing
Explanation: Packing should provide high area and free space while remaining light and retaining only a small amount of liquid.
Correct answer: Hold up large amount of liquid in the packing