Free Mass Transfer Operations MCQs with Answers
669 Mass Transfer Operations MCQs from Chemical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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- A. Cast iron packed tower
- B. Stainless steel plate tower
- C. None of these
- D. Packed steel tower lined with acid proof bricks
Explanation: SO₃ absorption in concentrated sulphuric acid is carried out in a packed tower to provide a large gas-liquid contact area.
Correct answer: Packed steel tower lined with acid proof bricks- A. Chemical stoneware
- B. Cast iron
- C. Karbate
- D. Mild steel
Explanation: Chemical stoneware is resistant to concentrated sulphuric acid and is therefore used as packing in the SO₃ absorption tower.
Correct answer: Chemical stoneware- A. Iron impregnated with resin (usually Bakelite)
- B. An intimate mixture of saw dust and iron dust (i.e. moist ferric hydroxide)
- C. Carbon free iron
- D. None of these
Explanation: Bog iron is hydrated ferric oxide, commonly supported or mixed with sawdust to provide a porous contact mass.
Correct answer: An intimate mixture of saw dust and iron dust (i.e. moist ferric hydroxide)24. Which of the following is not an advantage of fluidisation from transfer operation point of view ?
- A. Intimate contact of the fluid with all parts of the solid particles
- B. Prevention of particle segregation
- C. Minimisation of temperature variation
- D. Lower fluid pumping power requirement
Explanation: Fluidisation often improves contact, temperature uniformity, and resistance to segregation, but it generally requires substantial fluid…
Correct answer: Lower fluid pumping power requirement- A. 1
- B. <1
- C. 0
- D. >1
Explanation: For a saturated liquid feed, the entire feed enters as liquid, so the thermal condition parameter is q = 1.
Correct answer: 1- A. 5
- B. 20
- C. 35
- D. 55
Explanation: A partition in a Lessing ring adds internal contact surface without greatly increasing the packing volume.
Correct answer: 20- A. Silica gel
- B. Bog iron (i.e., moist ferric hydroxide)
- C. Basalt
- D. Diatomaceous earth
Explanation: Moist ferric hydroxide, or bog iron, absorbs hydrogen sulphide and other sulphur compounds by forming iron sulphides.
Correct answer: Bog iron (i.e., moist ferric hydroxide)- A. Absorbing in vetro-coke solution
- B. Adsorbing on bog iron bed
- C. Scrubbing with wash oil (a petroleum product)
- D. None of these
Explanation: Naphthalene is removed from coke-oven gas by absorption in wash oil, a petroleum fraction that dissolves the hydrocarbon vapours.
Correct answer: Scrubbing with wash oil (a petroleum product)- A. Decolourisation of sugar
- B. Solvent recovery from air and gases
- C. Absorption of gases and vapor
- D. Electrode manufacture
Explanation: Activated carbon is widely used for sugar decolourisation, gas and vapour adsorption, and solvent recovery.
Correct answer: Electrode manufacture- A. Sling psychrometer
- B. Chromatograph
- C. Mass spectrometer
- D. Polarimeter
Explanation: A sling psychrometer uses wet-bulb and dry-bulb temperatures to determine relative humidity and other humidity properties of air.
Correct answer: Sling psychrometer- A. Solute concentration
- B. Temperature
- C. Both A. & B.
- D. Neither A. nor B.
Explanation: The distribution coefficient is affected by temperature and can also vary with solute concentration when activity effects, association, or…
Correct answer: Both A. & B.- A. Normal condensation
- B. Wetting
- C. Difference of A. and B.
- D. Sum of A. and B.
Explanation: Adsorption caused by van der Waals attraction is analogous to condensation, while capillary adsorption involves wetting of the surface.
Correct answer: Sum of A. and B.- A. Product enrichment
- B. Yield enhancement
- C. Heat conservation
- D. None of these
Explanation: Returning part of the distillate as reflux increases liquid-vapour contact and gives repeated enrichment of the more volatile component.
Correct answer: Product enrichment- A. Dry bulb temperature
- B. Wet bulb temperature
- C. Humidity
- D. Relative saturation
Explanation: Adiabatic evaporation into unsaturated air at constant pressure follows an approximately constant wet-bulb temperature path because the…
Correct answer: Wet bulb temperature- A. 17
- B. 20
- C. 25
- D. 34
Explanation: For saturated vapour, use the water partial pressure of 2.34 kPa in n = pV/RT, giving about 960 mol of water.
Correct answer: 17- A. Temperature at constant humidity
- B. Humidity at constant temperature
- C. Temperature and the humidity
- D. All A., B. & C.
Explanation: Humid-gas enthalpy contains both the sensible enthalpy of the gas, which rises with temperature, and the water-vapour contribution, which…
Correct answer: All A., B. & C.- A. Removal of pure solvent by evaporation
- B. All A., B. & C.
- C. Changing the nature of the system by the addition of a more soluble material
- D. Change of temperature thereby causing super-saturation
Explanation: Crystallisation requires creating supersaturation, which can be achieved by evaporating solvent, cooling the solution, or adding another…
Correct answer: All A., B. & C.- A. Stripping
- B. Differential distillation
- C. Leaching
- D. Absorption
Explanation: Leaching transfers a soluble component from a solid into a liquid solvent, making it the reverse-direction counterpart of crystallising a…
Correct answer: Leaching- A. Nature of both the gas & the liquid
- B. Temperature
- C. Total pressure
- D. None of these
Explanation: The composition of a saturated gas depends on the vapour pressure of the liquid, the molecular weights of the gas and vapour, temperature…
Correct answer: None of these- A. Temperature vs. log (vapor pressure)
- B. Vapor pressure vs. log (temperature)
- C. Log (temperature) vs. log (vapor pressure)
Explanation: A Cox chart linearizes vapour-pressure data by plotting temperature against the logarithm of vapour pressure, which is especially useful…
Correct answer: Temperature vs. log (vapor pressure)