Mass Transfer

71.At a fixed total pressure, humidity depends only on the

1. Partial pressure of vapour in the mixture
2. Heat capacity of the vapour
3. Density of the vapour
4. None of these

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72.At a given equilibrium pressure, with increase in temperature, the concentration of adsorbed gas on solid adsorbent

1. Increases
2. Decreases
3. Remains unchanged
4. Increases exponentially

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73.At constant pressure, with increase of temperature, the dew point will

1. Increase
2. Decrease
3. Remain unchanged
4. Increase/decrease; depends on the temperature

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74.At equilibrium the concentration of water in vapour phase (C^*) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C^* = 0.0667m. To maintain dry conditions in a room of air space 100m³ containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is

1. 0
2. 0.2
3. 0.4
4. 1

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75.At minimum reflux ratio for a given separation

1. Number of plates is zero
2. Number of plates is infinity
3. Minimum number of the theoretical plates is required
4. Separation is most efficient

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76.At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes

1. 1
2. 0
3. ∞
4. None of these

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77.At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid _________ that in dry packed tower.

1. Is greater than
2. Is lower than
3. Is same as
4. Cannot be predicted as data are insufficient

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78.At what percentage (by volume) of alcohol composition, it forms an azeotrope with water?

1. 90
2. 91.5
3. 95
4. 99

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79.At what value of reflux ratio, number of theoretical plates in a distillation column is minimum?

1. 0
2. 1
3. ∞
4. < 1

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80.Azeotropism for ethyl alcohol-water system disappears by

1. Increasing temperature
2. Decreasing pressure
3. Increasing pressure
4. No means

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