Mass Transfer

501.The Schmidt number which is defined as, µ/ρ D, is the ratio of the

1. Momentum diffusivity to the mass diffusivity
2. Thermal diffusivity to the mass diffusivity
3. Momentum diffusivity to the thermal diffusivity
4. None of these

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502.The slope of 9-line is determined by the

1. Reflux ratio
2. Plate efficiency to be achieved
3. Thermal condition of the feed
4. Relative volatility

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504.The solvent used in liquid extraction should not have high latent heat of vaporisation, because

1. The pressure drop and hence the pumping cost will be very high
2. It cannot be recovered by distillation
3. Its recovery cost by distillation may be prohibitively high
4. It will decompose while recovering by distillation

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505.The solvent used in liquid-liquid extraction should have _________ less than one.

1. Selectivity
2. Distribution co-efficient
3. Both (A) and (B)
4. Neither (A) nor (B)

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506.The suitable evaporator for concentration of foaming liquids is a _________ evaporator.

1. Long tube
2. Short tube
3. Vacuum
4. Falling film

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507.The surface renewal frequency in Danckwerts' model of mass transfer is given by (KL: mass transfer co-efficient)

1. √(KL ².D^A)
2. KL ².D^A
3. KL ²/D^A
4. KL/D^{A 2}

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508.The temperature of water cooled in cooling tower is always _________ temperature of entering air.

1. More than the wet bulb
2. Less than the wet bulb
3. Equal to the wet bulb
4. Equal to the dry bulb

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509.The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the _________ temperature.

1. Dew point
2. Wet bulb
3. Dry bulb
4. None of these

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510.The term "approach" in a cooling tower refers to the difference in the temperature of the

1. Cold water leaving the tower and the wet bulb temperature of the surrounding air
2. Hot water entering the tower and the wet bulb temperature of the surrounding air
3. Hot water entering and the cooled water leaving the cooling tower
4. None of these

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