Mass Transfer

51.Agitator is provided in a crystalliser for

1. Avoiding deposition on cooler surfaces
2. Formation of nuclei
3. Crystal growth
4. All (A), (B) and (C)

View answer

52.Air at a particular humidity is heated in a furnace. The new dew point

1. Decreases
2. Increases
3. Depends on the extent of heating
4. Remain unchanged

View answer

53.Air initially at 101. 3 kPa and 40°C and with a relative humidity of 50%, is cooled at constant pressure to 30°C. The cooled air has a

1. Higher dew point
2. Higher absolute (specific) humidity
3. Higher relative humidity
4. Higher wet bulb temperature

View answer

54.Alcohol is dehydrated using _________ distillation.

1. Extractive
2. Azeotropic
3. Steam
4. Molecular

View answer

55.All moisture in a non-hygroscopic material is the _________ moisture.

1. Free
2. Equilibrium
3. Unbound
4. Bound

View answer

56.Ammonia present in the coke oven gas is removed by washing with

1. Caustic solution
2. Dilute ammoniacal liquor
3. Dilute HCl
4. Ethanolamine

View answer

57.An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively. The humidity of air sample expressed as kg of water vapour/kg of dry air is:

1. 0.048
2. 0.079
3. 0.122
4. 0.152

View answer

58.An alkaline solution is used to reduce the concentration of carbon dioxide in a stream from 10% to 0.1% by absorption with irreversible chemical reaction. The overall number of transfer units based on gas phase is:

1. 9.21
2. 4.605
3. 100
4. 0.001

View answer

59.An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii)

1. Less number of trays are required
2. Composition of the residue remains unchanged
3. More number of trays are required but the residue composition remains unchanged
4. More number of trays are required and the residue composition is more dilute in methanol

View answer

60.An Azeotropic mixture is a _________ mixture.

1. Binary
2. Ternary
3. Constant boiling point
4. None of these

View answer