Mass Transfer

431.The binary diffusivity in gases at atmospheric conditions is about

  1. 10-9 cm/sec
  2. 10-1 cm2/sec
  3. 10-3 sec/cm
  4. 10-4 cm2/sec2

Correct answer: (B)
10-1 cm2/sec

432.The binary diffusivity in gases does not depend upon the

  1. Pressure
  2. Temperature
  3. Nature of the components
  4. None of these

Correct answer: (D)
None of these

433.The boiling points of pure components of a binary system _________ with increase in total pressure of the system.

  1. Decreases
  2. Increases
  3. Remains unchanged
  4. May increase or decrease, depends on the system

Correct answer: (B)
Increases

434.The caking of crystals can be prevented by

  1. Maintaining high critical humidity
  2. Maintaining low critical humidity
  3. Coating the product with inert material
  4. Both (A) and (C)

Correct answer: (D)
Both (A) and (C)

435.The change in enthalpy per unit weight of adsorbed gas when adsorbed on gas free or "outgassed" adsorbent to from a definite concentration of adsorbate is called its

  1. Integral heat of adsorption
  2. Heat of wetting
  3. Differential heat of adsorption
  4. Heat of normal condensation

Correct answer: (A)
Integral heat of adsorption

436.The change in enthalpy, when a unit quantity of gas is absorbed by relatively large quantity of adsorbent (on which a definite concentration of the adsorbed gas already exists) is termed as the

  1. Differential heat of adsorption
  2. Heat of wetting
  3. Integral heat of adsorption
  4. None of these

Correct answer: (A)
Differential heat of adsorption

437.The commonly used solvent in supercritical extraction is

  1. Methyl ethyl ketone
  2. Water
  3. Carbon tetrachloride
  4. Carbon dioxide

Correct answer: (D)
Carbon dioxide

438.The cooling effect in a cooling tower can be speeded up by

  1. Increasing the air velocity and area of exposed wet surface
  2. Reducing the barometric pressure
  3. Reducing the humidity of the air
  4. All (A), (B) and (C)

Correct answer: (D)
All (A), (B) and (C)

439.The cooling effect in a cooling tower cannot be increased by

  1. Increasing the air velocity over the wet surfaces
  2. Reducing the humidity of entering air
  3. Lowering the barometric pressure
  4. None of these

Correct answer: (D)
None of these

440.The critical moisture content in case of drying indicates the _________ rate period.

  1. Beginning of falling
  2. Beginning of constant
  3. End of falling
  4. None of these

Correct answer: (A)
Beginning of falling

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