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 290 of 350
- A. Dynamic viscosity
- B. Kinematic viscosity
- C. Surface tension
- D. Pressure
Explanation: Mass diffusivity has dimensions of area per time, m²/s. Kinematic viscosity has the same dimensions, whereas dynamic viscosity, surface…
Correct answer: Kinematic viscosity- A. Kc = Kp = Km
- B. Kc = Kp/RT = Km . RT/P
- C. Kc = Kp . RT = Km . RT/p
- D. None of these
Explanation: For an ideal gas, concentration is related to pressure by C = p/RT, while mole fraction is related by y = p/P.
Correct answer: Kc = Kp . RT = Km . RT/p- A. All A., B. & C.
- B. Velocity
- C. Temperature
- D. Humidity
Explanation: Constant drying conditions require the surrounding air properties that control drying to remain fixed, including temperature, humidity…
Correct answer: All A., B. & C.- A. Increases
- B. Decreases
- C. Remain same
- D. Either A. or B., depends on the system
Explanation: At a fixed temperature, adsorption generally increases with equilibrium pressure because more adsorbate molecules are available at the…
Correct answer: Decreases- A. Separation of the constituents is the most effective
- B. Amount of solvent required will be minimum
- C. No separation will occur
- D. Solvent flow rate should be very low
Explanation: Selectivity measures how preferentially the solvent extracts one solute over another.
Correct answer: No separation will occur5786. Mass transfer co-efficient is directly proportional to DAB according to the __________ theory?
- A. None of these
- B. Penetration
- C. Surface-renewal
- D. Film
Explanation: In film theory, the mass-transfer coefficient is approximately k = D/δ, where δ is the stagnant-film thickness, so it is directly…
Correct answer: Film- A. Podbielniak
- B. Scheibel
- C. Treybal
- D. None of these
Explanation: The Podbielniak extractor is a rotating centrifugal contactor that uses centrifugal force to contact and separate the two liquid phases.
Correct answer: Podbielniak- A. Maximum
- B. Minimum
- C. Infinite
- D. Zero
Explanation: At minimum reflux, the required reflux flow and hence the reboiler and condenser duties are minimized, so the operating cost is minimum.
Correct answer: Minimum- A. 0.54
- B. 1.04
- C. 1.24
- D. 1.94
Explanation: For equal drug volume, the initial dissolution rate is proportional to exposed surface area.
Correct answer: 1.24- A. Increases
- B. Decreases
- C. Remains unchanged
- D. Decreases exponentially
Explanation: For most partially miscible liquid pairs, increasing temperature increases mutual solubility by making mixing more favorable.
Correct answer: Increases5791. The diffusivity D. in a binary gas mixture is related to the pressure (P) as__________________?
- A. D ∝ P0.5
- B. D ∝ 1/P
- C. D ∝ 1/P0.5
- D. D ∝ 1/P1.5
Explanation: Gas-phase diffusivity varies approximately inversely with total pressure because increasing pressure reduces the mean free path of…
Correct answer: D ∝ 1/P- A. Yes
- B. Normally not; but is possible if infinite number of plates are put
- C. Never
- D. Yes; if the reflux ratio is maximum
Explanation: Plate efficiency is the actual separation achieved divided by the ideal equilibrium-stage separation, so it cannot exceed 100 percent.
Correct answer: Never- A. Decreased solute solubility
- B. Large minimum liquid to gas (L/G) ratio
- C. Large number of trays
- D. All A., B. and C.
Explanation: Heat evolution raises the liquid temperature and usually lowers solute solubility, reducing the absorption driving force.
Correct answer: All A., B. and C.- A. Winkelmann's
- B. Gilliland's
- C. Wetted wall column
- D. Wike's
Explanation: Winkelmann's method determines vapor diffusivity experimentally by observing the evaporation or movement of a liquid-vapor boundary in a…
Correct answer: Winkelmann's- A. Small sizes
- B. Multi-component distillation
- C. High pressure operation
- D. Vacuum distillation
Explanation: Packed columns provide a large contact area with relatively low pressure drop, but their practical use in distillation is generally…
Correct answer: Small sizes- A. Sieve plate
- B. Pulsed column
- C. Mixer-settler
- D. Bollman
Explanation: A pulsed column enhances mixing and mass transfer through repeated pulsations, making it suitable for liquid-liquid extraction of…
Correct answer: Pulsed column- A. Uranium from its ore
- B. Mustard oil from mustard seed
- C. Ammonia from coke oven gas
- D. Water from petrol
Explanation: Water can be removed from petrol by adsorption on materials such as silica gel or molecular sieves.
Correct answer: Water from petrol- A. Pure component
- B. Binary mixture
- C. Ternary mixture
- D. Insoluble binary system
Explanation: At a ternary diagram vertex, the concentration of one component is 100% and the other two are zero.
Correct answer: Pure component- A. 1.5
- B. -0.6
- C. -1.5
- D. 0.6
Explanation: The q-line slope is q/(q−1). Since 40% of the feed is vapour, q, the liquid fraction, is 0.60, giving 0.60/(0.60−1) = −1.5.
Correct answer: -1.5- A. All liquid-liquid diffusion systems
- B. Absorption of NH3 from air by water
- C. Separation of a binary mixture by distillation
- D. All liquid-solid diffusion systems
Explanation: Binary distillation commonly involves equimolal counterdiffusion because the molar liquid and vapour flow rates remain approximately…
Correct answer: Separation of a binary mixture by distillation