Mass Transfer

521.The-relative volatility for separation of a non-ideal binary mixture by distillation should be

1. 0
2. 1
3. > 1
4. < 1

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522.Though, theoretically the adsorption & desorption isotherms is expected to coincide but sometimes at least a part of the isotherms does not coincide and this phenomenon is known as adsorption hysteresis. In such cases, the desorption equilibrium pressure is _________ that obtained for adsorption.

1. Lower than
2. Higher than
3. Same as
4. Either same or higher than

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523.To get high tray efficiency

1. Interfacial surface between liquid and gas phase should be large
2. Time of contact between the two phases should be less
3. Gas velocity should be very low
4. Liquid entrainment should be severe

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524.To increase the absorption factor, (where, G = gas flow rate, S = solvent flow rate)

1. Increase both 'G' and 'S'
2. Decrease both 'G' and 'S'
3. Increase 'S' and decrease 'G'
4. Increase 'G' and decrease 'S'

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525.To remove all the moisture from a wet solid it requires exposure to _________ air.

1. Perfectly dry
2. Highly humid
3. High temperature
4. None of these

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526.Total reflux in a distillation operation requires minimum

1. Reboiler load
2. Number of plates
3. Condenser load
4. All (A), (B) and (C)

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527.Tower diameter may be decreased by

1. Using higher reflux ratio
2. Use of increased tray spacing
3. Increasing the liquid flow rate
4. Increasing the vapour flow rate

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528.Tray spacing in a distillation column of dia 10-12 ft. used in petroleum refinery may be around _________ inches.

1. 5
2. 30
3. 60
4. 100

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529.Under conditions of flooding in packed tower, the gas pressure drop

1. Decreases rapidly
2. Increases rapidly
3. Remain constant
4. Is maximum

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530.Unit of molal diffusivity is

1. cm²/sec gm . mole
2. gm moles/cm² . sec
3. gm moles/cm. sec
4. gm moles/cm². sec

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