Mass Transfer

271.In liquid-liquid extraction, the number of phases at plait point is

1. 1
2. 2
3. 3
4. 4

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272.In McCabe-Thiele method of theoretical plate calculation for a distillation column, the operating lines of stripping and rectifying sections coincide with the diagonal at _________ reflux.

1. Total
2. Minimum
3. Operating
4. Maximum permissible

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273.In McCabe-Thiele method, at infinite reflux ratio

1. Number of plates is maximum
2. Overhead product is maximum
3. Both the operating lines coincide with the diagram
4. None of these

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274.In most of the mechanically agitated liquid-liquid extractors, baffles or horizontal compartmental plates are provided, which helps in

1. Reducing the axial mixing
2. Increasing the rate of extraction
3. Maintaining the concentration difference between the two phases
4. All 'a', 'b' & 'c'

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275.In most of the vacuum crystalliser, vacuum is generally produced by means of a

1. Suction pump
2. Compressed air jet
3. Steam jet ejector with a barometric condenser
4. None of these

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276.In paper industry, paper is dried in a _________ dryer.

1. Tunnel
2. Heated cylinder
3. Conveyor
4. Festoon

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277.In physical terms, Schmidt number means

1. Thermal diffusivity/mass diffusivity
2. Thermal diffusivity/momentum diffusivity
3. Momentum diffusivity/mass diffusivity
4. Mass diffusivity/thermal diffusivity

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278.In rectifying section of a continuous distillation column, the

1. Vapour is enriched with low boilers
2. Vapour is enriched with high boilers
3. Liquid is stripped of high boilers
4. None of these

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279.In saturated gas, the

1. Vapour is in equilibrium with the liquid at the gas temperature
2. Vapour is in equilibrium with the liquid at the room temperature
3. Partial pressure of vapour equals the vapour pressure of the liquid at room temperature
4. None of these

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280.In steam distillation, the

1. Temperature is 100°C
2. Temperature is more than 100° C
3. Product must be immiscible with water
4. Temperature is higher than the boiling point of either component

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