Mass Transfer

81.Back-trapping in a distillation column

1. Increases tray efficiency
2. Decreases tray efficiency
3. Reduces pressure drop
4. Is desirable, as it provides improved vapour-liquid contact

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82.Batch tray dryers suffers from the disadvantage of

1. High maintenance cost
2. Non-uniform & low production rate
3. High labour cost & low heat economy
4. All 'a', 'b' & 'c'

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83.Berl saddle made of carbon cannot be used for

1. Alkalis
2. SO₂
3. H2SO4
4. Oxidising atmosphere

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84.Binary distillation involves the mass transfer by _________ at the gas-liquid interface.

1. Unidirectional diffusion from liquid to gas phase
2. Unidirectional diffusion from gas to liquid phase
3. Either 'a' or 'b'
4. A counter diffusion at an almost equal molar rate

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85.Blowdown in a cooling tower

1. Means discarding a small fraction of circulating water to prevent and limit the concentration of salt and impurities
2. Increases the scale forming tendencies of water
3. Is undesirable
4. All (A), (B) & (C)

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86.Boiling point diagram is not affected by the ambient

1. Pressure
2. Humidity
3. Temperature
4. Both (B) and (C)

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87.Bollman extractor

1. Is a static bed leaching equipment
2. Is used for extraction of oil from oilseed
3. Is a centrifugal extractor
4. Employs only counter-current extraction

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88.Bound moisture is that liquid which exerts an equilibrium vapor pressure _________ that of the pure liquid at the given temperature.

1. Less than
2. More than
3. Equal to
4. Either (A) or (B); depends on the solid

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89.Calcium ammonium nitrate (a fertiliser) is dried in a _________ dryer.

1. Rotary
2. Vacuum
3. Tunnel
4. Tray

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90.Calculation of mass transfer co-efficient is mostly/normally done using _________ theory.

1. Surface renewal
2. Film
3. Penetration
4. None of these

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