Generic selectors
Exact matches only
Search in title
Search in content
Search in posts
Search in pages
Filter by Categories
nmims post
Objective Type Set
Online MCQ Assignment
Question Solution
Solved Question
Uncategorized

Multiple choice question for engineering

Set 1

1. Which components of cell help in the manufacturing of new biological products?
a) Carbohydrates
b) Proteins
c) Lipids
d) Nucleic acids

View Answer

Answer: b [Reason:] Proteins such as enzymes play a very important role in manufacturing of biological products, they provide the quality and stability with increased product efficiency and reducing consumption in energy, water and raw materials- and generating less waste.

2. Which of the following activity is not considered in Protein Fractionation which is routinely used in proteomic research?
a) Reduce the size of the protein pool to be analyzed
b) Remove highly expressed proteins
c) Bring Low abundant proteins into dynamic range
d) Bring High abundant proteins into dynamic range

View Answer

Answer: d [Reason:] The low abundant proteins are preferred over high abundant proteins as the low abundant proteins prove to be informative biomarkers and enrichment of low abundant proteins has the great advantage of obtaining much larger amount of material that can be used for further fractionations and analyses.

3. The genetic information of the Plasmid is essential to survival of the host cells?
a) True
b) False

View Answer

Answer: b [Reason:] Plasmid is an extra chromosomal circular DNA molecules which are not part of the bacterial genome but carry functions advantageous to the host such as: produce enzymes which degrade antibiotics or heavy metals and they are used in recombinant DNA as they can replicate independently of the host chromosome.

4. Which chemical is usually used before Bacterial transformation process?
a) Calcium chloride
b) Potassium chloride
c) Ferric chloride
d) Sodium chloride

View Answer

Answer: a [Reason:] Before Bacterial transformation, bacteria are treated with a chemical called Calcium chloride , which causes water to enter into the cells and makes them swell . These swollen bacteria are then known as competent bacteria, which is further used in Bacterial transformation process .

5. Why the shake flask is not continuously preferred?
a) Because of resistant to growth
b) Because of increase rate of contamination
c) Because of imprecise control of temperature
d) Because of unlimited stirring

View Answer

Answer: c [Reason:] Shake flasks are usually subject to media evaporative loss in warmer culture environments, typically 10% of volume per 24 hr at 37 °C. This loss changes the density of the culture and prohibits longer term operation of the system and also the temperature control is absent or limited.

6. Which process is also called product recovery?
a) Upstream processing
b) Mid-stream processing
c) Downstream processing
d) Biological processing

View Answer

Answer: c [Reason:] Downstream processing implies manufacture of a purified product fit for a specific use, generally in marketable quantities, it also refers to the recovery and purification of biosynthetic products, particularly pharmaceuticals, from natural sources such as animal or plant tissue or fermentation broth, including the recycling of salvageable components and the proper treatment and disposal of waste.

7. The scale-up process is preferred to which condition?
a) The migration of a process from the lab-scale to the pilot plant-scale
b) The migration of a process from the bench-scale to the lab-scale
c) The migration of a process from the small-scale to the lab-scale
d) The migration of a process from the bench-scale to the small-scale

View Answer

Answer: a [Reason:] In scale-up process, product and process development tend to move forward in small steps, this reduces the risk with larger investments in the next step and production level improvement.

8. Which type of fermentation is preferred in bench top fermenter?
a) Batch
b) Fed-batch
c) Continuous
d) Dual or multiple-fermentation

View Answer

Answer: b [Reason:] Fed-batch fermentation is superior to conventional batch fermentation when controlling concentrations of a nutrient (or nutrients) affect the yield or productivity of the desired metabolite. The advantage of the fed-batch fermentation is that one can control concentration of fed-substrate in the culture liquid at arbitrarily desired levels.

9. The bench-top bioreactor comes under which type of bioreactor?
a) Solid-state bioreactor
b) Photo bioreactors
c) Airlift bioreactors
d) Stirred tank bioreactors

View Answer

Answer: d [Reason:] The bench-top bioreactor is mechanically stirred tank bioreactor fitted with a sparger and a rushton turbine. And its volume varies from < 1-L to 10,000-L capacity. The air is added to the culture medium under pressure through a device called sparger. The sparger may be a ring with many holes or a tube with a single orifice. The sparger along with impellers (agitators) enables better gas distribution system throughout the vessel.

10. From the following volumes, which capacity the Pilot-scale bioreactor holds?
a) 100-1000L
b) 1000-10000L
c) 1-100L
d) less than 1L

View Answer

Answer: a [Reason:] The Pilot-scale bioreactor vessel of capacity 100-1000L is built according to specifications determined from the bench-scale prototype.

11. Which of the following does not comes under the product of Recombinant mammalian cells?
a) Bovine somatotropin
b) Erythropoietin
c) Growth hormone
d) Tissue plasminogen activator

View Answer

Answer: a [Reason:] Bovine somatotropin is the peptide hormone produced by cows pituitary gland and is used in regulating metabolic processes and mainly comes under the animal recombinants.

Set 2

1. Which of the following is correct related to transgene?
a) Phenotype remains unaltered
b) Phenotype changes
c) Produced within an organism
d) Genotype changes

View Answer

Answer: b [Reason:] A transgene is a gene or genetic material that has been transferred naturally, or by any of a number of genetic engineering techniques from one organism to another. The introduction of a transgene (called “transgenesis”) has the potential to change the phenotype of an organism.

2. Lentivirus and Retrovirus are related.
a) True
b) False

View Answer

Answer: a [Reason:] Lentiviruses are a subtype of retrovirus.

3. Lentivirus and Retrovirus are not different.
a) True
b) False

View Answer

Answer: b [Reason:] The main difference between lentiviruses and standard retroviruses from an experimental standpoint is lentiviruses are capable of infecting non-dividing and actively dividing cell types, whereas standard retroviruses can only infect mitotically active cell types.

4. Which of the following virus is not used in gene therapy?
a) Papillomavirus
b) Retrovirus
c) Adenovirus
d) Herpes simplex virus

View Answer

Answer: a [Reason:] Some of the viruses currently used in gene therapy include retroviruses, adenoviruses, adeno-associated viruses and the herpes simplex virus.

5. Along with Retrovirus, Herpes simplex virus is also enveloped.
a) True
b) False

View Answer

Answer: a [Reason:] Animal herpes viruses all share some common properties. The structure of herpes viruses consists of a relatively large double-stranded, linear DNA genome encased within an icosahedral protein cage called the capsid, which is wrapped in a lipid bilayer called the envelope. The envelope is joined to the capsid by means of a tegument. This complete particle is known as the virion.

6. Which of the following is true for heterologous proteins?
a) It occurs naturally in the cell
b) It express the protein
c) It does not express the protein
d) It makes protein

View Answer

Answer: c [Reason:] In cell biology and protein biochemistry, heterologous expression means that a protein is experimentally put into a cell that does not normally make (i.e., express) that protein.

7. Endocytosis and phagocytosis are not related terms.
a) True
b) False

View Answer

Answer: b [Reason:] Endocytosis is a form of active transport in which a cell transports molecules (such as proteins) into the cell (endo- + cytosis) by engulfing them in an energy-using process. Endocytosis and its counterpart, exocytosis, are used by all cells because most chemical substances important to them are large polar molecules that cannot pass through the hydrophobic plasma or cell membrane by passive means. Endocytosis includes pinocytosis (cell drinking) and phagocytosis (cell eating).

8. In coated pits, the cytoplasmic surface is coated with:
a) Calcium
b) Clathrin
c) Clathrim
d) Clathrix

View Answer

Answer: b [Reason:] Coated pits are regions of the cell membrane specialized in receptor-mediated endocytosis. Their cytoplasmic surface is coated with a bristlelike structure made of clathrin.

9. What is the pH of early endosomes?
a) 5.0
b) 4.5
c) 6.0
d) 7.5

View Answer

Answer: c [Reason:] The intravesicular pH drops along the endocytic pathway, from pH 6.0–6.5 in early endosomes.

10. What is the pH of late endosomes?
a) 3.0
b) 4.5
c) 6.0
d) 7.5

View Answer

Answer: b [Reason:] The intravesicular pH drops along the endocytic pathway,from pH 4.5–5.5 in late endosomes and lysosomes.

11. What are lipid rafts?
a) Solid particles
b) Low concentration of cholesterol
c) Low concentration of glycosphingolipids
d) High concentration of cholesterol

View Answer

Answer: d [Reason:] Lipid rafts are subdomains of the plasma membrane that contain high concentrations of cholesterol and glycosphingolipids. They exist as distinct liquid-ordered regions of the membrane that are resistant to extraction with nonionic detergents.

12. The division of retrovirus is limited in invivo condition.
a) True
b) False

View Answer

Answer: a [Reason:] The resulting retrovirus vector can be used only with dividing cells, since cells must undergo mitosis before gene integration can occur. This feature limits in vivo use to cases such as cancer suppression but is not a limitation on ex vivo systems.

13. Which of the following virus is less affected?
a) Less mutated virus
b) Medium mutated virus
c) High mutated virus
d) Non-mutated virus

View Answer

Answer: c [Reason:] Viral decay acceleration (VDA) is a therapeutic strategy which increases the mutation frequency of a virus toward an error catastrophe threshold. The high mutation rate increases diversity within the viral population and facilitates survival in the face of host immune responses, depletion of target cells and antiviral therapeutics. This evolutionary advantage however comes at a considerable cost in that the vast majority of virus particles has mutated beyond a survivability threshold and is therefore non-infectious. Laboratory studies have demonstrated that therapeutics capable of increasing the mutation frequency as little as 2-fold results in collapse of the viral population. This therapeutics, termed VDA agents, accelerate the accumulation of additional mutations in the viral genome, progressively debilitating the virus which causes decay and eventual extinction of the entire viral population.

14. Proteoglycans are the survival factor of viruses.
a) True
b) False

View Answer

Answer: b [Reason:] The proteoglycans have very high molecular weight. If the virus is concentrated by ultrafiltration, the proteoglycan is also concentrated by nearly the same factor. While the high virus concentration would be expected to increase the number of infected cells, the presence of concentrated proteoglycan leads to increased inhibition of infection, so that the number of cells infected does not increase significantly and in some cases even decreases with the concentrated viral preparation.

15. Which of the following is correct?
a) Viral decay is not sensitive to temperature
b) Virus production is sensitive to temperature
c) Virus decay is sensitive to temperature
d) Viral production and decay increase with temperature

View Answer

Answer: c [Reason:] Both the rate of virus production and viral decay decrease with temperature, the rate of decay is more sensitive to temperature. Thus the amount of potentially active virus is severalfold higher when produced at 28°C. However, the transduction efficiency did not increase, presumably due to changes in proteoglycan concentration.

Set 3

1. The heat diffusion is which type of process?
a) Conduction
b) Convection
c) Radiation
d) Osmosis

View Answer

Answer: b [Reason:] Convection is usually the dominant form of heat transfer in liquids and gases. Although often discussed as a distinct method of heat transfer, convective heat transfer involves the combined processes of unknown conduction (heat diffusion) and advection (heat transfer by bulk fluid flow).

2. The immobilized cells have different temperature gradient.
a) True
b) False

View Answer

Answer: b [Reason:] Kinetic parameters for enzyme and cell reactions are strong functions of temperature. If temperature in the particle varies, different values of the kinetic parameters must be applied. However, as temperature gradients generated by immobilised cells and enzymes are generally negligible, assuming constant temperature throughout the particle is reasonable.

3. The effective diffusivity of substrate in the solid, DAc is dependent of substrate.
a) True
b) False

View Answer

Answer: b [Reason:] The value of DAc is a complex function of the molecular- diffusion characteristics of the substrate, the tortuousness of the diffusion path within the solid, and the fraction of the particle volume available for diffusion. DAc is constant and independent of substrate concentration in the particle; this means that DAc does not change with position.

4. Enzyme is immobilised in 8 mm diameter agarose beads at a concentration of 0.018 kg protein m-3 gel. Ten beads are immersed in a well-mixed solution containing 3.2 ×10-3 kg m-3 substrate. The effective diffusivity of substrate in agarose gel is 2.1 × 10-9 m2 s– 1. Kinetics of the enzyme can be approximated as first order with specific rate constant 3.11 × 105 s– 1 per kg protein. Mass transfer effects outside the particles are negligible. Estimate the volume per bead.
a) 2.65×10-7 m3
b) 2.66×10-7 m3
c) 2.67×10-7 m3
d) 2.68×10-7 m3

View Answer

Answer: d [Reason:] R= 4×10-3 m; DAc = 2.1×10-9 m2 s-1. In the absence of external mass-transfer effects, CAs = 3.2×10-3 kg m-3.

Volume per bead = 4/3 π R3 = 4/3 π (4×10-3 m)3= 2.68×10-7 m3.

5. Refer to Q4 and Estimate the amount of enzyme present.
a) 4.81×10-8 kg
b) 4.83×10-8 kg
c) 4.85×10-8 kg
d) 4.87×10-8 kg

View Answer

Answer: b [Reason:] 10 beads have volume 2.68×10-6 m3. The amount of enzyme present is:

2.68 ×10-6 m3 (0.018 kgm-3) =4.83 × 10-8 kg.

6. Refer to Q4 and Q5, and Estimate the intrinsic first-order rate constant “k1”.
a) 0.005 s-1
b) 0.015 s-1
c) 0.025 s-1
d) 0.035 s-1

View Answer

Answer: b [Reason:] k I = 3.11×105/sup> s-1kg-1(4.83 x 10-8 kg) =0.015 s-1.

7. The unit of intrinsic factor “k” remains constant in every order.
a) True
b) False

View Answer

Answer: b [Reason:] k1 is the intrinsic first-order rate constant with dimensions T-1, whereas, k0 is the intrinsic zero-order rate constant with units of, for example, g mol s-1 m-3 particle.

8. Non-viable yeast cells are immobilised in alginate beads. The beads are stirred in glucose medium under anaerobic conditions. The effective diffusivity of glucose in the beads depends on cell density according to the relationship:

DAc = 6.33- 7.17yC
where DAc is effective diffusivity ×1010 m2 s-1 and yC is the weight fraction of yeast in the gel. Rate of glucose uptake can be assumed to be zero order; the rate constant at a yeast density in alginate of 15 wt% is 0.5 g l-1 min-1. For maximum reaction rate, the concentration of glucose inside the particles should remain above zero. Estimate the value of k0, Converting k0 to units of kg, m and is ___
a) 8.33 x 10-3 kg m-3 s-1
b) 6.33 x 10-3 kg m-3 s-1
c) 4. 33 x 10-3 kg m-3 s-1
d) 2.33 x 10-3 kg m-3 s-1

View Answer

Answer: a bioprocess-engineering-questions-answers-internal-mass-transfer-reaction -q8

9. The concept of overall coefficient of heat transfer is used in heat transfer problems of
a) Conduction
b) Convection
c) Radiation
d) Conduction and convection

View Answer

Answer: d [Reason:] The overall heat transfer by combined Modes is usually expressed on terms of an overall conductance or overall heat transfer coefficient ‘U’. There are numerous methods for calculating the heat transfer coefficient in different heat transfer modes, different fluids, flow regimes, and under different thermohydraulic conditions. Often it can be estimated by dividing the thermal conductivity of the convection fluid by a length scale.

10. The natural convection air cooled condensers are used in ________
a) Water coolers
b) Domestic refrigerator
c) Room air conditioners
d) Water boilers

View Answer

Answer: b [Reason:] Air cooled condensers are of two types: natural convection and forced convection. In the natural convection type, the air flows over it in natural a way depending upon the temperature of the condenser coil. In the forced air type, a fan operated by a motor blows air over the condenser coil.

11. Concentration at the surface of the spherical catalyst will be higher than the inside of the catalyst.
a) True
b) False

View Answer

Answer: a [Reason:] Concentration at the pore mouth will be higher than that inside the pore, .i.e., internal diffusion which is diffusion of reactants or products from particle surface (pore mouth) to pellet interior. And Mole balance over the shell thickness Dr is: IN – OUT + GEN = ACCUM.

12. To increase the overall rate of a rxn limited by internal diffusion the reaction should not ______
a) decrease the radius R
b) increase the concentration of A
c) increase the radius R
d) increase the temperature

View Answer

Answer: c [Reason:] Internal diffusion limits the observed rate when decreasing dp increases –r’A . If the rate increases when dp decreases but does not change with FT0, then larger dp is limited by internal diffusion. (where, FT0 is the particle size, dp is the diameter and –r’A is the reaction rate).

Set 4

1. The inactive cells are advantageous for enzyme activity.
a) True
b) False

View Answer

Answer: a [Reason:] In some cases, it may be more advantageous to use inactive (dead or resting) cells with the desired enzyme activity in immobilized form. This approach eliminates costly enzyme separation and purification steps and is therefore economically more feasible.

2. Which of the following does not produces “Proteases”?
a) Bacillus
b) Rhizopus
c) Mucor
d) Bacillus coagulans

View Answer

Answer: d [Reason:] A process in which a mutant atypical Bacillus coagulans strain is cultivated in a growth medium free of xylose. The invention relates to glucose isomerase, to methods for the production of this enzyme and to enzymatic isomerization of glucose to fructose with glucose isomerase.

3. Cellulase is used in which type of industry?
a) Food industry
b) Paper industry
c) Biofuel industry
d) Chemical industry

View Answer

Answer: c [Reason:] Cellulase is used in biofuel industry and its application is class of enzymes that degrade cellulose to glucose monomers.

4. Which of the following is not included in immobilization process?
a) Absorption
b) Adsorption
c) Entrapment
d) Affinity

View Answer

Answer: a [Reason:] Despite their excellent catalytic capabilities, enzymes and their properties must be improved prior to industrial implementation in many cases. Some aspects of enzymes that must be improved prior to implementation are stability, activity, inhibition by reaction products, and selectivity towards non-natural substrates. This may be accomplished through immobilization of enzymes on a solid material, such as a porous support. Immobilization of enzymes greatly simplifies the recovery process, enhances process control, and reduces operational costs. Many immobilization techniques exist, such as adsorption, covalent binding, affinity, and entrapment.

5. In Upstream processes, process development increases the mRNA hydrolysis and proteolysis?
a) True
b) False

View Answer

Answer: b [Reason:] Process development is typically performed after genetic modification of the source organism, and involves the modification of the culture medium and growth conditions. In many cases, process development aims to reduce mRNA hydrolysis and proteolysis.

6. Which of the following is not an upstream process?
a) Selection of a suitable enzyme
b) Process development
c) Concentration and primary purification of enzymes
d) Large scale production

View Answer

Answer: c [Reason:] Downstream processes are those that contribute to separation or purification of enzymes. Depending on the intended use of the enzyme, different levels purity is required. For example, enzymes used for diagnostic purposes must be separated to a higher purity than bulk industrial enzymes to prevent catalytic activity that provides erroneous results.

7. Which of the following purified enzyme is used in pharmaceutical industry?
a) Subtilisin
b) Novozym-435
c) Bromelain
d) Asparaginase

View Answer

Answer: d [Reason:] Asparaginase enzyme as a desired product is used in pharmaceutical industry as an application for lymphatic cancer therapeutic.

8. Which type of fermentation is used for large scale manufacturing of enzymes?
a) Solid-state fermentation
b) Submerged fermentation
c) Solid-Gas state fermentation
d) Gas-state fermentation

View Answer

Answer: b [Reason:] Submerged fermentation is a method of manufacturing biomolecules in which enzymes and other reactive compounds are submerged in a liquid such as alcohol, oil or a nutrient broth. The process is used for a variety of purposes, mostly in industrial manufacturing.

9. Which enzyme was first produced industrially?
a) Bacteria enzyme
b) Yeast enzyme
c) Fungal enzyme
d) Streptomyces

View Answer

Answer: c [Reason:] Microbial enzymes have been utilized for many centuries without knowing them fully. The first enzyme produced industrially was taka-diastase (a fungal amylase) in 1896, in United States. It was used as a pharmaceutical agent to cure digestive disorders.

10. The production of enzyme is mostly carried out by?
a) Batch fermentation
b) Continuous fermentation
c) Fed-batch fermentation
d) Semi-batch fermentation

View Answer

Answer: a [Reason:] The medium can be sterilized by employing batch or continuous sterilization techniques. The fermentation is started by inoculating the medium. The growth conditions (pH, temperature, O2 supply, nutrient addition) are maintained at optimal levels. The froth formation can be minimised by adding antifoam agents. The production of enzymes is mostly carried out by batch fermentation and to a lesser extent by continuous process.

11. Which is the inducer of enzyme invertase?
a) Starch
b) Sucrose
c) Galactosidases
d) Fatty acids

View Answer

Answer: b [Reason:] Invertase is an enzyme that catalyzes the hydrolysis (breakdown) of sucrose. The resulting mixture of fructose and glucose is called inverted sugar syrup. For industrial use, invertase is usually derived from yeast. The inducer compounds are expensive and their handling (sterilization, addition at specific time) also is quite difficult.

12. What do you mean by “Nutrient repression”?
a) Inhibition of unwanted enzyme production
b) Production of unwanted enzymes
c) Inhibition of cell nutrients
d) Production of waste

View Answer

Answer: a [Reason:] The native metabolism of microorganism is so devised that there occurs no production of unnecessary enzymes. In other words, the microorganisms do not synthesize enzymes that are not required by them, since this is a wasteful exercise. The inhibition of unwanted enzyme production is done by nutrient repression. The nutrients may be carbon, nitrogen, phosphate or sulfate suppliers in the growth medium. For large scale production of enzymes, nutrient repression must be overcome.

13. What is the method of screening?
a) To improve the microbial strain
b) To improve the growth of an enzyme
c) To choose appropriate microorganisms for the desired enzyme
d) To determine the optimum conditions for growth of microbes

View Answer

Answer: c [Reason:] Screening is one of the key optimization parameters to understand the dynamics of the process, allowing for rapid understanding and enhancement of process conditions by analyzing culture metabolic rates and metabolites.

14. System of reaction in which no reactant leaves reaction mixture is termed as ___________
a) Open system
b) Closed system
c) Semi-open system
d) Partially closed system

View Answer

Answer: b [Reason:] One of the fundamental foundations of bioprocess system design is the use of “closed” systems for production. As a key element of Good Manufacturing Practice (GMP) compliance, closed systems and equipment are utilized to prevent contamination of the product.

15. Which of the following is true for single cell protein?
a) Algae cannot be used in single cell protein
b) It is produced through fermentation
c) It does not contain carbohydrates and vitamins
d) Its utilization increases environmental pollution

View Answer

Answer: b [Reason:] Single-cell proteins develop when microbes ferment waste materials (including wood, straw, cannery, and food-processing wastes, residues from alcohol production, hydrocarbons, or human and animal excreta). The problem with extracting single-cell proteins from the wastes is the dilution and cost. They are found in very low concentrations, usually less than 5%. Engineers have developed ways to increase the concentrations including centrifugation, flotation, precipitation, coagulation, and filtration, or the use of semi-permeable membranes.

Set 5

1. The ratio of inertial forces to viscous forces is called as ________
a) Nusselt number
b) Schmidt number
c) Sherwood number
d) Reynolds number

View Answer

Answer: d [Reason:] The Reynolds number is the ratio of inertial forces to viscous forces and is a convenient parameter for predicting if a flow condition will be laminar or turbulent. It can be interpreted that when the viscous forces are dominant (slow flow, low Re) they are sufficient enough to keep all the fluid particles in line, and then the flow is laminar. Even very low Re indicates viscous creeping motion, where inertia effects are negligible. When the inertial forces dominate over the viscous forces (when the fluid is flowing faster and Re is larger) then the flow is turbulent.

2. Which number is analogous to Reynold’s number?
a) Nusselt number
b) Schmidt number
c) Sherwood number
d) Grashof number

View Answer

Answer: d [Reason:] The Grashof number (Gr) is a dimensionless number in fluid dynamics and heat transfer which approximates the ratio of the buoyancy to viscous force acting on a fluid. It frequently arises in the study of situations involving natural convection and is analogous to the Reynolds number.

3. Which number is defined as the ratio of momentum diffusivity to thermal diffusivity?
a) Prandtl number
b) Nusselt number
c) Reynold’s number
d) Sherwood number

View Answer

Answer: a [Reason:] The Prandtl number (Pr) or Prandtl group is a dimensionless number, It is defined as the ratio of momentum diffusivity to thermal diffusivity. That is, the Prandtl number is given as:

bioprocess-engineering-questions-answers-liquid- solid-mass-transfer-correlations-q3

where: v : momentum diffusivity (kinematic viscosity), v = μ/ρ, (SI units: m2/s) α : thermal diffusivity,α= k/(cp ρ) , (SI units: m2/s) μ : dynamic viscosity, (SI units: Pa s = N s/m2) k : thermal conductivity, (SI units: W/m-K) cp : specific heat, (SI units: J/kg-K) ρ : density, (SI units: kg/m3).

4. Which number is analogous to Prandlt number in terms of mass transfer?
a) Sherwood number
b) Schmidt number
c) Reynolds number
d) Nusselt number

View Answer

Answer: b [Reason:] Schmidt Number, Sc, is a dimensionless parameter representing the ratio of diffusion of momentum to the diffusion of mass in a fluid. It is defined as Sc = v/δ where ν is kinematic viscosity and δ diffusivity.

Schmidt number is the mass transfer equivalent of Prandtl Number. For gases, Sc and Pr have similar values (≈0.7) and this is used as the basis for simple heat and mass transfer analogies.

5. What is the unit of slip velocity?
a) m min
b) m2/ min
c) m/min
d) m/min2

View Answer

Answer: c [Reason:] The rate, expressed in feet (meters) per minute, at which a given size and shape of rock particle will descend or settle in water; e.g., the slip velocity in water of a round, flat particle of rock, 1/2 in (1.27 cm) in diameter, is about 54 ft/min (16.5 m/min).

6. Overall heat transfer coefficient is associated with?
a) Conduction and radiation
b) Conduction and convection
c) Convection and radiation
d) Radiation

View Answer

Answer: b [Reason:] The overall heat transfer coefficient U is a measure of the overall ability of a series of conductive and convective barriers to transfer heat. It is commonly applied to the calculation of heat transfer in heat exchangers.

7. Evaporation of n-propyl alcohol into carbon dioxide for the same geometrical arrangement of tube diameter (d) of 38 mm when the carbon dioxide flows at a maximum velocity (ug) of 10 m/s at 300 K and 1 atm. Properties of dilute mixtures of propyl alcohol in carbon dioxide at 300 K and 1 atm are: Molecular weight (M) = 44 gm/mole, density (ρ) = 1.8 kg/m3 , Viscosity (μ) = 1.49×10-5 kg/m.s, diffusivity (DAB) = 7.6×10-6 m2 /s and universal gas constant (R) = 8.314 J/mole.K. Estimate the Reynolds number.
Nu = 0.453Re0.568 Pr0.36, where 10 < Re (= ρug d/μ)<106 and 0.7 < Pr < 500
a) 45906.04
b) 40906.05
c) 45906.05
d) 40906.04

View Answer

Answer: a [Reason:] Re = 1.8*10*0.038/1.49×10-5 = 45906.04.

8. Refer to Q7 and Calculate the value of Schmidt number (Sc).
a) 1.02
b) 1.04
c) 1.06
d) 1.08

View Answer

Answer: d [Reason:] Sc = (1.49×10-5 )/(1.8* 7.6×10-6 ) = 1.08.

9. Refer to Q7 and Q8 and calculate the mass-transfer coefficient by using the mass and heat transfer analogy.
a) 1.661×10-05 mole/m2 .s.Pa
b) 1.663×10-05 mole/m2 .s.Pa
c) 1.665×10-05 mole/m2 .s.Pa
d) 1.669×10-05 mole/m2 .s.Pa

View Answer

Answer: c [Reason:] Analogy to heat transfer

Sh = 0.453 Re0.568 Sc0.36 = 207.68

So, kG RTd/ DAB = 207.68

Therefore, kG = (207.68*DAB) / RTd = 1.665×10-05 mole/m2 .s.Pa.

10. Advection is related to Convection.
a) True
b) False

View Answer

Answer: a [Reason:] The term advection sometimes serves as a synonym for convection, but technically, convection covers the sum of transport both by diffusion and by advection. Advective transport describes the movement of some quantity via the bulk flow of a fluid (as in a river or pipeline).

11. Nusselt number is the mass transfer analog of which number?
a) Sherwood number
b) Schmidt number
c) Reynolds number
d) Nusselt number

View Answer

Answer: a [Reason:] The Sherwood number (Sh) (also called the mass transfer Nusselt number) is a dimensionless number used in mass-transfer operation. It represents the ratio of the convective mass transfer to the rate of diffusive mass transport.