Molecular distillation is
(A) High temperature distillation
(B) For heat-sensitive materials
(C) Very low pressure distillation
(D) Both (B) and (C)
Description : High pressure at the bottom of a distillation tower handling heat sensitive materials results in (A) Thermal decomposition of bottoms (B) Increased relative volatility (C) Erosion of the tower (D) Very efficient operation
Last Answer : (A) Thermal decomposition of bottoms
Description : Heat sensitive materials with very high latent heat of vaporisation may be economically separated using (A) Liquid extraction (B) Distillation (C) Evaporation (D) Absorption
Last Answer : (A) Liquid extraction
Description : Dowtherm is a (A) High temperature heating medium (a petroleum product) (B) Product of coal tar distillation (C) Very heat sensitive material (D) None of these
Last Answer : Option A
Description : Vacuum is generally maintained in the vapour space of an evaporator mainly to (A) Get economical temperature difference by using moderate pressure steam (B) Facilitate forward ... (C) Concentrate heat sensitive materials (D) Achieve very high concentration of the final product
Last Answer : (A) Get economical temperature difference by using moderate pressure steam
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 : Crude oil is subjected to vacuum distillation in the last stage, because (A) High boiling point products like heavy fuel oil & lubricating oils are heat sensitive and may decompose (B) Lighter/low ... prone to thermal decomposition (C) High purity products can be obtained thereby (D) None of these
Last Answer : (A) High boiling point products like heavy fuel oil & lubricating oils are heat sensitive and may decompose
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 : For a binary mixture with low relative volatility, (A) Use steam distillation (B) Use molecular distillation (C) Use high pressure distillation (D) An azeotrope may be formed during distillation
Last Answer : (D) An azeotrope may be formed during distillation
Description : Pick out the wrong statement: (A) The capacity of an evaporator is reduced by the boiling point elevation (B) Corrosive liquid is normally passed through the tubes in a ... recompression evaporator (D) Heat sensitive materials should be concentrated in high pressure evaporators
Last Answer : (D) Heat sensitive materials should be concentrated in high pressure evaporators
Description : Heat sensitive materials can be concentrated in an evaporator employing (A) Vacuum (B) High pressure (C) High residence time (D) None of these
Last Answer : (A) Vacuum
Description : The solvent used in liquid extraction should not have high latent heat of vaporisation, because (A) The pressure drop and hence the pumping cost will be very high (B) It cannot ... by distillation may be prohibitively high (D) It will decompose while recovering by distillation
Last Answer : (C) Its recovery cost by distillation may be prohibitively high
Description : Enzymes are (A) Proteins with high molecular weight (around 10,000) (B) Derived from living organisms (C) Catalyst for temperature sensitive reactions (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Pick out the correct statement. (A) Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of ... Flash distillation is suitable for separating components which have very close boiling temperature
Last Answer : (A) Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of nonideal binary system by distillation
Description : Pick out the wrong statement. (A) A particular chemical reaction is more temperature sensitive at low temperatures (B) A very high value of equilibrium constant, K (K >> 1) indicates that the ... ) Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant regions
Last Answer : (C) The intercept of the Arrhenius plot is called the 'activation energy
Description : Steam distillation is not recommended to be used, if the (A) Azeotropic mixture is to be separated and the final product is miscible with water (B) Liquids decompose, if ... unstable or has the tendency to react with other components associated with it, at the boiling temperature
Last Answer : (A) Azeotropic mixture is to be separated and the final product is miscible with water
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 : Heat sensitive materials like certain pharmaceuticals and food stuffs can be dried in a/an __________ dryer. (A) Indirect tray (B) Spray (C) Freeze (D) None of these
Last Answer : (C) Freeze
Description : Entrainer used in Azeotropic distillation should (A) Form a low boiling azeotrope with one of the constituents of the mixture (B) Form a new azeotrope of low relative volatility with one of the ... (C) Have high latent heat of vaporisation (D) Have high viscosity to provide high tray efficiency
Last Answer : (A) Form a low boiling azeotrope with one of the constituents of the mixture
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 : Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when (A) Extracting solvent is cheaply & abundantly available ... very high (D) One of the liquid components has very high affinity towards the solvent
Last Answer : (D) One of the liquid components has very high affinity towards the solvent
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 : 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 : Components, having widely different boiling point in a binary mixture, can be separated using __________ distillation. (A) Molecular (B) Extractive (C) Steam (D) Simple
Last Answer : (D) Simple
Description : In case of __________ distillation, a solvent is added to alter the relative volatility of the mixture to be separated. (A) Molecular (B) Azeotropic (C) Extractive
Last Answer : (C) Extractive
Description : Alcohol is dehydrated using __________ distillation. (A) Extractive (B) Azeotropic (C) Steam (D) Molecular
Last Answer : (B) Azeotropic
Description : Rayleigh equation applies to __________ distillation. (A) Differential (B) Flash (C) Equilibrium (D) Molecular
Last Answer : (A) Differential
Description : Rose oil is extracted from rose leaves using __________ distillation. (A) High pressure (B) Low pressure (C) Extractive (D) Steam
Last Answer : (D) Steam
Description : The reason for preferring packed towers over plate towers in distillation practice is that the packed tower operation gives (A) Low pressure drop and high hold up (B) High pressure drop and low hold ... C) Low pressure drop and low hold up (D) High pressure drop and high hold up
Last Answer : (C) Low pressure drop and low hold up
Description : Low-temperature ____ evaporators are used for heat-sensitive foods. a. ultrafiltration c. vacuum b. osmosis d. drum
Last Answer : c. vacuum
Description : Fruit juice (a heat sensitive material) can be concentrated in a __________ evaporator. (A) Long tube (B) Falling film (C) High pressure (D) None of these
Last Answer : (B) Falling film
Description : Pick out the correct statement. (A) Reactions with high activation energies are very temperature sensitive (B) Chemical equilibrium is a static state (C) A photochemical reaction is catalysed by ... occurs when the energy of the reacting molecule is less than the activation energy of the reaction
Last Answer : (A) Reactions with high activation energies are very temperature sensitive (B) Chemical equilibrium is a static state
Description : Pick out the wrong statement: (A) Chemical reactions with high activation energy are very temperature sensitive (B) A flat velocity profile exists in a plug flow reactor (C) The residence ... D) Half life of a reaction increases with increased initial concentration for reaction orders more than one
Last Answer : (C) The residence time for all the elements of fluid in case of a P.F.R. need not be same
Description : Reactions with high activation energy are (A) Very temperature sensitive (B) Temperature insensitive (C) Always irreversible (D) Always reversible
Last Answer : (A) Very temperature sensitive
Description : The following statement(s) is/are true concerning newer detection methods of systemic infection. a. Enzyme-linked immunosorbent assay (ELISA) is a rapid immunologic assay used for ... detected using advanced molecular techniques include cytomegalovirus (CMV) and human immunodeficiency virus (HIV)
Last Answer : Answer: a, b, c, d Although the classic detection of infection based on clinical signs of infection and bacterial culture remain the most common clinical tools, increasing ... including CMV and HIV. Furthermore, preliminary investigations into possible detection of fungal pathogens are underway
Description : Pick out the wrong statement regarding the solubility characteristics of high polymers. (A) Greater the degree of cross-linking in the polymer, lesser is its solubility (B) Polymers having more ... of the solvent (D) High molecular weight polymers on dissolving gives solution of very low viscosity
Last Answer : (D) High molecular weight polymers on dissolving gives solution of very low viscosity
Description : What is the major cause of 'October Heat'? (1) Hot and dry weather (2) Very low velocity winds (3) Low pressure systems over the IndoGangetic plains (4) High temperature associated with high humidity
Last Answer : (4) High temperature associated with high humidity Explanation: The months of OctoberNovember mark a period of transition from hot rainy season to cold dry winter conditions. This period is ... temperature and high humidity, weather becomes oppressive. This phenomenon is known as 'October heat.
Description : The amount of steam required per unit quantity of distillate in case of steam distillation will be reduced by (A) Raising the temperature (B) Lowering the total pressure (C) Both (A) and (B) (D) Neither (A) nor (B)
Last Answer : (C) Both (A) and (B
Description : Gas thermometers are more sensitive than the liquid thermometers because the gases – (1) have large coefficient of expansion (2) are lighter (3) have low specific heat (4) have high specific heat
Last Answer : (1) have large coefficient of expansion Explanation: Gases are more sensitive to the temperature than liquids (such as mercury). That means gas expands more than the mercury for the same increase of temperature. Hence the has thermometer is more sensitive than liquid (mercury) thereto-meter.
Description : Gas thermometers are more sensitive than the liquid thermometers because of the gases - (1) have low specific heat (2) have high specific heat (3) have large coefficient of expansion (4) are lighter
Last Answer : (1) have low specific heat Explanation: Gas thermometers are more sensitive because gas has low specific heat than liquids.
Description : Gas thermometers are more sensitive than the liquid thermometers because the gases (1) have large coefficient of expansion (2) are lighter (3) have low specific heat (4) have high,specific heat
Last Answer : have large coefficient of expansion
Description : The polysulfide rubber impression materials are: A. Not sensitive to temperature when curing B. Quite sensitive to temperature when curing C. Less sensitive to temperature than silicone rubber D. The same sensitivity to temperature as silicone rubber E. None of the above
Last Answer : B. Quite sensitive to temperature when curing
Description : Pitch (a product of coal tar distillation) is always mixed with creosote oil, when it is to be burnt in a burner, because (A) Its calorific value is very less (B) Tar neutralises the residual acids ... for its transportation through pipelines at economic pressure drop (D) All (A), (B) and (C)
Last Answer : (C) It reduces viscosity and imparts fluidity for its transportation through pipelines at economic pressure drop
Description : Pick out the wrong statement. (A) Different solids have different equilibrium moisture curves (B) Total condenser or reboiler is considered equivalent to one theoretical plate in McCabe-Thiele method of ... (D) Even a forced draft cooling tower cannot cool water below the wet bulb temperature
Last Answer : (C) Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column
Description : Distillation at reduced pressure is used for liquids which (a) Have high boiling points (b) Have low boiling points (c) Have high volatility (d) Decompose before their boiling points
Last Answer : Ans:(d)
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 : Waxes present in petroleum products (A) Can be separated out by distillation (B) Are not soluble in them (C) Crystallise out at low temperature (D) Decrease their viscosity
Last Answer : (C) Crystallise out at low temperature
Description : According to Avogadro's Hypothesis (a) the molecular weights of all the perfect gases occupy the same volume under same conditions of pressure and temperature (b) the sum of partial pressure of ... gases have two values of specific heat (e) all systems can be regarded as closed systems.
Last Answer : Answer : a
Description : The advantage of backward feed multiple effect evaporators over forward feed units is that (A) Heat sensitive material can be handled (B) There is no additional cost of pumping ... liquid is at highest temperature (D) Equal heat transfer co-efficients exist in various effects
Last Answer : (C) Most concentrated liquid is at highest temperature
Description : Pick out the wrong statement. Generally for physical adsorption, a gas of (A) Higher molecular weight is adsorbed in preference to a gas of low molecular weight (B) High critical temperature ... volatility is adsorbed in preference to a gas of high volatility (D) None of these
Last Answer : (D) None of these