In rectifying section of a continuous distillation column, the
(A) Vapour is enriched with low boilers
(B) Vapour is enriched with high boilers
(C) Liquid is stripped of high boilers
(D) None of these
Description : In stripping section of continuous distillation column, the (A) Liquid is stripped of high boiler (B) Liquid is enriched with high boiler (C) Vapour is stripped of low boiler (D) None of these
Last Answer : (B) Liquid is enriched with high boiler
Description : 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. (A) Total (B) Minimum (C) Operating (D) Maximum permissible
Last Answer : (A) Total
Description : Pick out the correct statement. (A) The slope of the stripping line is always less than unity (B) For a given separation in a binary distillation column, with increase in reflux ratio ( ... (D) Kremser-Brown-Souder's equation is used to calculate the efficiency of a plate tower
Last Answer : C) In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux
Description : Back-trapping in a distillation column (A) Increases tray efficiency (B) Decreases tray efficiency (C) Reduces pressure drop (D) Is desirable, as it provides improved vapour-liquid contact
Last Answer : (B) Decreases tray efficiency
Description : For a distillation column operating at minimum reflux, the (A) Concentration of liquid and vapour leaving a plate will be same (B) Reflux ratio will be maximum (C) Number of plates required will be maximum
Last Answer : (C) Number of plates required will be maximum
Description : As the reflux ratio in a distillation column is increased from the minimum, the (A) Slope of the operating line in stripping section decreases (B) Number of plates decreases very slowly first ... decreases and then increases (D) Liquid flow increases while the vapor flow decreases for a system
Last Answer : (C) Total cost first decreases and then increases
Description : For a binary mixture with low relative volatility, continuous rectification to get pure products will require (A) Low reflux ratio (B) Less number of trays (C) Small cross-section column (D) High reflux ratio
Last Answer : (D) High reflux ratio
Description : Inside the distillation column, the (A) Driving force for the vapour flow is the pressure drop (B) Liquids are not always at their bubble points (C) Pressure increases gradually from bottom to the top of the column (D) None of these
Last Answer : (A) Driving force for the vapour flow is the pressure drop
Description : In a binary distillation column, if the feed contains 40 mole % vapour, the q line will have a slope of (A) 1.5 (B) -0.6 (C) -1.5 (D) 0.6
Last Answer : (C) -1.5
Description : In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapour, because (A) Temperature is less (B) Total pressure is less (C) Mixing of steam ... not so intimate as to result in equilibrium condition (D) Saturated steam is used for steam distillation
Last Answer : (C) Mixing of steam with the material being vaporised is not so intimate as to result in equilibrium condition
Description : Pick out the wrong statement. (A) In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed (B) In ... layers over a flat plate are of equal thickness, if Schmidt number is equal to unity
Last Answer : (C) For Laminar flow over a plate of length L, the local mass transfer coefficient at a distance L from the leading edge is 1.5 × 10 -2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10 -2m/s
Description : Pick out the wrong statement. (A) Critical moisture content is not a property of the material itself (B) A sharp increase in pressure drop gives an indication of the flooding in a ... unity (D) Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum
Last Answer : (D) Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum
Description : Weeping in a distillation column (A) Increases tray efficiency (B) Provides large interfacial surface for mass transfer (C) Results due to very high gas velocity (D) Results due to very low gas velocity
Last Answer : (D) Results due to very low gas velocity
Description : When the feed to a distillation column is a saturated liquid, slope of thefeed line is (A) Zero (B) Unity (C) Infinity (D) None of these
Last Answer : (C) Infinity
Description : In an operating distillation column, the (A) Vapors and liquids are at their dew point and bubble point respectively (B) Driving force for the liquid flow is its specific weight (C) Driving force for ... bottom to the top of the column (D) Highest temperature is encountered at the top of the column
Last Answer : (C) Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column
Description : Pick out the wrong statement: (A) Reboiler is not used in open steam distillation (B) The separation of solutes of different molecular sizes in a liquid solution by use of a ... is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition
Last Answer : (D) Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition
Description : 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 ... and without total reflux (D) The top and bottom compositions correspond to the maximum enrichment available
Last Answer : (D) The top and bottom compositions correspond to the maximum enrichment available
Description : Pick out the wrong statement. (A) With decrease in feed temperature, the number of plates required for binary distillation decreases for a given L/V' ratio (B) The extraction per unit ... and its crosssection is wider at the bottom (D) Vander wall adsorption is also called chemisorption
Last Answer : (D) Vander wall adsorption is also called chemisorption
Description : Flooding in a distillation column is detected by a sharp (A) Increase in Murphree plate efficiency (B) Decrease in pressure drop (C) Decrease in liquid hold up in the column (D) Increase in pressure drop
Last Answer : (D) Increase in pressure drop
Description : Plate efficiency in a distillation column is reduced due to the __________ of liquid. (A) Entrainment (B) Foaming (C) Weeping & dumping (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
Description : The feed to fractionating column is changed from saturated vapour to saturated liquid. If the separation and reflux ratio remains unchanged, the number of ideal stages will (A) Increase (B) Decrease (C) Remain same (D) Depend on saturated boiling point; may increase or decrease
Last Answer : (A) Increase
Description : Reboiler is considered as one theoretical plate, because (A) Of the assumption that vapour and liquid leaving the reboiler are in equilibrium (B) Vapour is recycled to the column (C) Reboiler itself contains one plate (D) None of these
Last Answer : (A) Of the assumption that vapour and liquid leaving the reboiler are in equilibrium
Description : In distillation where q is defined as the moles of liquid flow in the stripping section per mole of feed introduced, for saturated liquid feed (A) q > 1 (B) q < 1 (C) q = 1 (D) q = 0
Last Answer : (C) q = 1
Description : Priming in a distillation column (A) Results from very low gas velocity (B) Is desirable from point efficiency consideration (C) Is characterised by the presence of foam throughout the space between trays (D) Reduces the overall pressure drop
Last Answer : (C) Is characterised by the presence of foam throughout the space between trays
Description : When the mixture to be distilled has a very high boiling point and the product material is heat sensitive, the separation technique to be used is __________ distillation. (A) Continuous (B) Steam (C) Azeotropic (D) None of these
Last Answer : (B) Steam
Description : Liquid metal (e.g., molten sodium) is preferred as a coolant in case of a/an __________ reactor. (A) Homogeneous (B) Graphite moderated (C) Fast breeder (D) Enriched uranium (3% U-235) fuelled
Last Answer : (C) Fast breeder
Description : Urea is formed only (A) In liquid phase (B) In vapour phase (C) At very high temperature (D) At very low pressure (vacuum)
Last Answer : (A) In liquid phase
Description : An ideal liquid refrigerant should (A) Not have a sub-atmospheric vapour pressure at the temperature in the refrigerator coils (B) Not have unduly high vapour pressure at the condenser temperature (C) Both (A) and (B) (D) Have low specific heat
Last Answer : (C) Both (A) and (B)
Description : Use of water as a manometric liquid suffers from the disadvantage of its (A) Low vapour pressure (B) Corrosive nature (C) High vapour pressure (D) High boiling point
Last Answer : (C) High vapour pressure
Description : Acetic acid will be most economically separated from a dilute solution of acetic acid in water by (A) Solvent extraction (B) Continuous distillation (C) Evaporation (D) Absorption
Last Answer : (A) Solvent extraction
Description : Rayleigh's equation applies to __________ distillation. (A) Continuous (B) Steam (C) Differential (D) Flash
Last Answer : (C) Differential
Description : Alcohol is used in manometers because (A) It has low vapour pressure (B) It is clearly visible (C) It has low surface tension (D) It can provide longer column due to low density
Last Answer : Answer: Option D
Description : Routine maintenance of a ship's service alternator should include ______________. A. changing the pedestal bearing insulation yearly B. megger testing of all rectifying diodes C. lubricating excitation slip rings D. periodic cleaning of the air filters or screens
Last Answer : Answer: D
Description : Common basic applications for the operational amplifier include ____________. A. counting, pulsing and clocking amplifiers B. summing, scaling and difference amplifiers C. step-up, step-down and rectifying amplifiers D. all of the above
Last Answer : Answer: B
Description : The targets of energy audit are…. a) Investigating problem b) Rectifying problem c) Analyzing problem d) None of the above
Last Answer : Investigating problem
Description : When a substance is added to a liquid medium which inhibits the growth of unwanted bacteriaand favors the growth of wanted bacteria, it is known as A- differential medium B- enriched medium C- enrichment medium D-selective medium
Last Answer : enrichment medium
Description : Which one of the following statements most accurately relates the properties of a liquid at room temperature with its vapour pressure? A A liquid with a low vapour pressure will probably have a ... with a high vapour pressure will probably have high intermolecular forces and a low boiling point.
Last Answer : A A liquid with a low vapour pressure will probably have a high surface tension and a high boiling point.
Description : Clausius-Clapeyron Equation gives accurate result, when the (A) Vapour pressure is relatively low and the temperature does not vary over wide limits (B) Vapour obeys the ideal gas law and the latent heat of ... is negligible compared with that in the vapour state (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : A reasonably general expression for vapour-liquid phase equilibrium at low to moderate pressure is φi yi P = Yi xifi° where, Φ is a vapor fugacity component, Yiis the liquid activity co- ... and liquid composition xi only (D) Temperature, pressure, liquid composition xi and vapour composition yi
Last Answer : (C) Temperature, pressure and liquid composition xi only
Description : Flooding in a column results due to (A) High pressure drop (B) Low pressure drop (C) Low velocity of the liquid (D) High temperature
Last Answer : (A) High pressure drop
Description : Bottom product of atmospheric pressure crude oil distillation column is termed as (A) Reduced crude (B) Heavy ends (C) Asphalt (D) Residuum
Last Answer : (A) Reduced crude
Description : Products drawn from the top to bottom of the crude oil distillation column has progressively increasing (A) Boiling points (B) Molecular weight (C) C/H ratio (D) All (A), (B) and (C)
Description : Vacuum maintained in the vacuum distillation column in oil refinery is in the range of about __________ mm Hg absolute. (A) 1 to 5 (B) 30 to 80
Last Answer : (B) 30 to 80
Description : In distillation column design, the McCabe-Thiele procedure is inadequate and a Ponchan-Savarit procedure is needed, when (A) Saturated feed is not used (B) An azeotrope forms (C) The latent ... vaporisation of the more and less volatile components are greatly different (D) A total condenser is used
Last Answer : (D) A total condenser is used
Description : The minimum number of theoretical plates is required for achieving a given separation in distillation column with (A) No reflux (B) Total reflux (C) Zero reflux ratio (D) Minimum reflux ratio
Last Answer : (B) Total reflux
Description : Overall efficiency of the distillation column is (A) The ratio of number of ideal plates to actual plates (B) The ratio of number of actual plates to ideal plates (C) Same as the Murphree efficiency (D) Always more than the point efficiency
Last Answer : (A) The ratio of number of ideal plates to actual plates
Description : If a1 and a2 are the relative volatilities when the pressure in the distillation column is 1 and 2 atm respectively. Pick out the correct statement. (A) a1 = a2 (B) a1 = 2a2 (C) a1 = 0.5 a2 (D) None of these
Last Answer : (D) None of these
Description : Fenske-Underwood equation used for calculating the minimum number of theoretical plates in distillation column is valid for (A) Constant molal overflow (B) Total reflux (C) Constant relative volatility (D) All (A), (B) and (C)
Description : For the same process conditions, the reflux ratio of an unlagged distillation column (A) Decreases in winter (B) Increases in winter (C) Increases in summer (D) None of these
Last Answer : (B) Increases in winter
Description : Fenske equation determines the (A) Maximum number of ideal plates (B) Height of the distillation column (C) Minimum number of theoretical plates (D) Optimum reflux ratio
Last Answer : (C) Minimum number of theoretical plates