7171. In batch distillation with constant reflux, overhead product composition __________ with time.
Increases
Decreases
Does not vary
May increase on decrease, depends on the system
✅ The correct answer is option B.
Chemical Engineering
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7172. The caking of crystals can be prevented by
Maintaining high critical humidity
Maintaining low critical humidity
Coating the product with inert material
Both A and C
✅ The correct answer is option D.
7173. Relative humidity is the ratio of the
Partial pressure of the vapour to the vapour pressure of the liquid at room temperature
Partial pressure of the vapour to the vapour pressure of the liquid at gas temperature
Actual humidity to saturation humidity
None of these
✅ The correct answer is option B.
7174. In an operating distillation column, the
Vapors and liquids are at their dew point and bubble point respectively
Driving force for the liquid flow is its specific weight
Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column
Highest temperature is encountered at the top of the column
✅ The correct answer is option C.
7175. A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped). At the new steady state,
Composition of vapors and that of liquid do not vary throughout the column
Reboiler load and condenser load are minimum
The top and bottom compositions are unchanged with and without total reflux
The top and bottom compositions correspond to the maximum enrichment available
✅ The correct answer is option D.
7176. When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30°C, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,
As the acetone concentration increases, the solubility curves approach each other
Both the phases become identical at a particular common point on both the solubility curves called the plait point
The distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x-y curve used in distillation and absorption termina
All of the above
✅ The correct answer is option D.
7177. The expression, y(1 – x)/x(1 – y) is for
Absorption factor
Relative volatility
Selectivity
Murphree efficiency
✅ The correct answer is option B.
7178. Blowdown in a cooling tower
Means discarding a small fraction of circulating water to prevent and limit the concentration of salt and impurities
Increases the scale forming tendencies of water
Is undesirable
All of the above
✅ The correct answer is option A.
7179. Can a cooling tower cool water below the wet bulb temperature of inlet air?
Yes
No
Yes ; but height of cooling tower will be prohibitively high
Yes ; but the air flow rate should be excessively high
✅ The correct answer is option B.
7180. Nitrobenzene (boiling point = 210.6°C) is steam distilled at 1 atm pressure.Nitrobenzene will distill off __________ °C.
At < 100
At > 210.6
Between 100 and 210
None of these
✅ The correct answer is option A.