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Answered
Review
Question 1 of 67
1. Question
1 points
Category: MATHEMATICS
The value of the following determinant :–
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Question 2 of 67
2. Question
1 points
Category: MATHEMATICS
The value of where is
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Question 3 of 67
3. Question
1 points
Category: THERMODYNAMICS
A reasonably general expression for vapour-liquid phase equilibrium at low to moderate pressures is Where Φi is a vapour fugacity coefficient, γi is the liquid activity coefficient, and fiº is the fugacity of pure component i. The Ki value (yi = Ki xi) is therefore in general, a function of
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Question 4 of 67
4. Question
1 points
Category: THERMODYNAMICS
High pressure steam is expanded adiabatically and reversibly through a well insulated turbine which produces some shaft work. If the enthalpy change and entropy change across the turbine are represented by ΔH and ΔS, respectively, for this process :
Correct
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Question 5 of 67
5. Question
1 points
Category: PROCESS CALCULATIONS
For the case of a fuel gas undergoing combustion with air, if the air/fuel ratio is increased, the adiabatic flame temperature will
Correct
Incorrect
Question 6 of 67
6. Question
1 points
Category: FLUID MECHANICS
The Power number for a stirred tank becomes constant at high Reynolds number. In this limit, the variation of power input with impeller rotational speed (N) is proportional to
Correct
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Question 7 of 67
7. Question
1 points
Category: FLUID MECHANICS
The operation of a rotameter is based on
Correct
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Question 8 of 67
8. Question
1 points
Category: FLUID MECHANICS
Applying a pressure drop across a capillary results in a volumetric flow rate Q under laminar flow conditions. The flow rate, for the same pressure drop, in a capillary of the same length but half the radius is
Correct
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Question 9 of 67
9. Question
1 points
Category: HEAT TRANSFER
The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by :–
Correct
higher the absorptivity(black), higher the emissivity
lower the absorptivity(white), lower the emissivity
Incorrect
higher the absorptivity(black), higher the emissivity
lower the absorptivity(white), lower the emissivity
Question 10 of 67
10. Question
1 points
Category: HEAT TRANSFER
Heat transfer by natural convection is enhanced in systems with
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Question 11 of 67
11. Question
1 points
Category: MASS TRANSFER
The surface renewal frequency in Danckwerts’ model of mass transfer is given by (kL ; mass transfer coefficient, m/s)
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Question 12 of 67
12. Question
1 points
Category: MASS TRANSFER
For gas absorption the height of a transfer unit, based on the gas phase, is given by (G: superficial molar gas velocity; L: superficial molar liquid velocity; FG: mass transfer coefficient, mol/m²s; a: interfacial area per unit volume of tower)
Correct
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Question 13 of 67
13. Question
1 points
Category: CHEMICAL REACTION ENGINEERING
The conversion for a second order, irreversible reaction (constant volume), in batch mode is given by
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Question 14 of 67
14. Question
1 points
Category: MASS TRANSFER
The Lewis relation for air-water humidification is given by (ky: Mass transfer coefficient of moisture in air; hG : heat transfer coefficient; CS : heat capacity of vapour gas mixture)
Correct
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Question 15 of 67
15. Question
1 points
Category: CHEMICAL REACTION ENGINEERING
The reaction rate constants at two different temperature T1 and T2 are related by
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Incorrect
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Question 16 of 67
16. Question
1 points
Category: CHEMICAL REACTION ENGINEERING
The E-curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt
Correct
Incorrect
Question 17 of 67
17. Question
1 points
Category: INSTRUMENTATION
The calibration data of a thermocouple with its cold junction at 0ºC are given below
The hot junction of the thermocouple is placed in a bath at 80ºC while its cold junction is at 20ºC. What is the emf of the thermocouple?
Correct
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Question 18 of 67
18. Question
1 points
Category: PROCESS CONTROL
A process is initially at steady state with its output y = 1 for an input u = 1. The input is suddenly changed to 2 at time t = 0. The output response is y(t) = 1 + 2t. The transfer function of the process is
Correct
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Question 19 of 67
19. Question
1 points
Category: FLUID MECHANICS
The inherent characteristics of an equal percentage value relating flow rate q with; valve stem movement x are described by the equation
Correct
Incorrect
Question 20 of 67
20. Question
1 points
Category: PLANT DESIGN
A perforated plate has holes of diameter dh arranged in a pitch ph. Each hole has tube of i.d., dt, passing through it. The ligament efficiency is given by
Correct
Incorrect
Question 21 of 67
21. Question
1 points
Category: PLANT DESIGN
The ends of a cylindrical vessel can be closed by a head, which can be one of the four shapes. For the same thickness, choose the one which can withstand the highest pressure
Correct
Pressure Vessel Heads Ellipsoidal Head, Hemispherical Head and Torispherical Head are three types of ASME Pressure Vessel Dished Heads. ELLIPSOIDAL HEAD This is also called a 2:1 elliptical head. The shape of this head is more economical, because the height of the head is just a quarter of the diameter. Its radius varies between the major and minor axis. HEMISPHERICAL HEAD A sphere is the ideal shape for a head, because the pressure in the vessel is divided equally across the surface of the head. The radius (R) of the head equals the radius of the cylindrical part of the vessel. TORISPHERICAL HEAD These heads have a dish with a fixed radius (CR), the size of which depends on the type of torispherical head. The transition between the cylinder and the dish is called the knuckle. The knuckle has a toroidal shape.
Incorrect
Pressure Vessel Heads Ellipsoidal Head, Hemispherical Head and Torispherical Head are three types of ASME Pressure Vessel Dished Heads. ELLIPSOIDAL HEAD This is also called a 2:1 elliptical head. The shape of this head is more economical, because the height of the head is just a quarter of the diameter. Its radius varies between the major and minor axis. HEMISPHERICAL HEAD A sphere is the ideal shape for a head, because the pressure in the vessel is divided equally across the surface of the head. The radius (R) of the head equals the radius of the cylindrical part of the vessel. TORISPHERICAL HEAD These heads have a dish with a fixed radius (CR), the size of which depends on the type of torispherical head. The transition between the cylinder and the dish is called the knuckle. The knuckle has a toroidal shape.
Question 22 of 67
22. Question
1 points
Category: ECONOMICS
An investment of Rs. 100 lakhs is to be made for construction of a plant which will take two years to start production. The annual profit from operation of the plant is Rs. 20 lakhs. What will be the payback time ?
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Question 23 of 67
23. Question
1 points
Category: CHEMICAL TECHNOLOGY
One of the steps during refining of cane sugar consists of addition of hydrated lime to the sugar syrup followed by carbonation of the resulting solution. The purpose of this step is to
Correct
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The juice from the mills, a dark green color, is acid and turbid. The clarification (or defecation) process is designed to remove both soluble and insoluble impurities (such as sand, soil, and ground rock) that have not been removed by preliminary screening. The process employs lime and heat as the clarifying agents. Milk of lime (about one pound per ton of cane) neutralizes the natural acidity of the juice, forming insoluble lime salts. Heating the lime juice to boiling coagulates the albumin and some of the fats, waxes, and gums, and the precipitate formed entraps suspended solids as well as the minute particles. The sugar beet solution, on the other hand, is purified by precipitating calcium carbonate, calcium sulfite, or both in it repeatedly. Impurities become entangled in the growing crystals of precipitate and are removed by continuous filtration.
The muds separate from the clear juice through sedimentation. The non-sugar impurities are removed by continuous filtration. The final clarified juice contains about 85 percent water and has the same composition as the raw extracted juice except for the removed impurities. To concentrate this clarified juice, about two-thirds of the water is removed through vacuum evaporation. Generally, four vacuum-boiling cells or bodies are arranged in series so that each succeeding body has a higher vacuum (and therefore boils at a lower temperature). The vapors from one body can thus boil the juice in the next one—the steam introduced into the first cell does what is called multiple-effect evaporation. The vapor from the last cell goes to a condenser. The syrup leaves the last body continuously with about 65 percent solids and 35 percent water. The sugar beet sucrose solution, at this point, is also nearly colorless, and it likewise undergoes multiple-effect vacuum evaporation. The syrup is seeded, cooled, and put in a centrifuge machine. The finished beet crystals are washed with water and dried.
Incorrect
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The juice from the mills, a dark green color, is acid and turbid. The clarification (or defecation) process is designed to remove both soluble and insoluble impurities (such as sand, soil, and ground rock) that have not been removed by preliminary screening. The process employs lime and heat as the clarifying agents. Milk of lime (about one pound per ton of cane) neutralizes the natural acidity of the juice, forming insoluble lime salts. Heating the lime juice to boiling coagulates the albumin and some of the fats, waxes, and gums, and the precipitate formed entraps suspended solids as well as the minute particles. The sugar beet solution, on the other hand, is purified by precipitating calcium carbonate, calcium sulfite, or both in it repeatedly. Impurities become entangled in the growing crystals of precipitate and are removed by continuous filtration.
The muds separate from the clear juice through sedimentation. The non-sugar impurities are removed by continuous filtration. The final clarified juice contains about 85 percent water and has the same composition as the raw extracted juice except for the removed impurities. To concentrate this clarified juice, about two-thirds of the water is removed through vacuum evaporation. Generally, four vacuum-boiling cells or bodies are arranged in series so that each succeeding body has a higher vacuum (and therefore boils at a lower temperature). The vapors from one body can thus boil the juice in the next one—the steam introduced into the first cell does what is called multiple-effect evaporation. The vapor from the last cell goes to a condenser. The syrup leaves the last body continuously with about 65 percent solids and 35 percent water. The sugar beet sucrose solution, at this point, is also nearly colorless, and it likewise undergoes multiple-effect vacuum evaporation. The syrup is seeded, cooled, and put in a centrifuge machine. The finished beet crystals are washed with water and dried.
Question 24 of 67
24. Question
1 points
Category: CHEMICAL TECHNOLOGY
Styrene is produced from ethyl-benzene by the process of
Correct
1ST EXPLANATION
Reaction is the reversible, endothermic conversion of ethylbenzene to styrene and hydrogen: C6H5CH2CH3 ⇔ C6H5CH=CH2 + H2 ∆H (600 °C) = 124.9 kJ/mol
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Incorrect
1ST EXPLANATION
Reaction is the reversible, endothermic conversion of ethylbenzene to styrene and hydrogen: C6H5CH2CH3 ⇔ C6H5CH=CH2 + H2 ∆H (600 °C) = 124.9 kJ/mol
2ND EXPLANATION
Question 25 of 67
25. Question
1 points
Category: CHEMICAL TECHNOLOGY
In the fluid catalytic cracker (FCC), the cracking reaction is – (A) – and the regeneration is – (B) –
Correct
1ST EXPLANATION
In FCC, a fluidized-bed (or fluid-bed) of catalyst particles is brought into contact with the gas oil feed along with injected steam at the entrance (called the riser) of the reactor. The hot catalyst particles coming from the regenerator unit evaporate the feed gas oil upon contact in the riser, and the cracking starts as the gas oil vapors and the catalyst particles move upward in the reactor. The temperature of the catalyst particles drops as the evaporation of gas oil and endothermic cracking reactions proceed during the upward movement. Cracking reactions also deposit a significant amount of coke on the catalysts, leading to the deactivation of the catalyst. After removing the adsorbed hydrocarbons by steam stripping, the coked catalyst is sent to the regeneration unit to burn off the coke with air. Heat released from burning the coke deposit increases the temperature of the catalyst particles that are returned to the riser to complete the cycle. Burning off the rejected carbon (coke) in the regenerator provides the energy necessary for cracking without much loss, thus increasing the thermal efficiency of the process. The cracking products are sent to the fractionator for recovery after they are separated from the catalyst particles in the upper section of the reactor .
In the reactor, the cracking reactions initiate on the active sites of the catalysts with the formation of carbocations and the subsequent ionic chain reactions produce branched alkanes and aromatic compounds to constitute the crackate (cracked gasoline with high octane number), light olefins, cycle oils, and slurry oil that are sent to the fractionator. A carbon-rich byproduct of catalytic cracking, termed “coke,” deposits on catalyst surfaces and blocks the active sites. FCC is considered a carbon rejection process because the coke deposited on the catalyst surface and eventually burned off for heat is rich in carbon and thus enables the production of large quantities of a light distillate (crackate) in the process without the addition of hydrogen.
2ND EXPLANATION
Incorrect
1ST EXPLANATION
In FCC, a fluidized-bed (or fluid-bed) of catalyst particles is brought into contact with the gas oil feed along with injected steam at the entrance (called the riser) of the reactor. The hot catalyst particles coming from the regenerator unit evaporate the feed gas oil upon contact in the riser, and the cracking starts as the gas oil vapors and the catalyst particles move upward in the reactor. The temperature of the catalyst particles drops as the evaporation of gas oil and endothermic cracking reactions proceed during the upward movement. Cracking reactions also deposit a significant amount of coke on the catalysts, leading to the deactivation of the catalyst. After removing the adsorbed hydrocarbons by steam stripping, the coked catalyst is sent to the regeneration unit to burn off the coke with air. Heat released from burning the coke deposit increases the temperature of the catalyst particles that are returned to the riser to complete the cycle. Burning off the rejected carbon (coke) in the regenerator provides the energy necessary for cracking without much loss, thus increasing the thermal efficiency of the process. The cracking products are sent to the fractionator for recovery after they are separated from the catalyst particles in the upper section of the reactor .
In the reactor, the cracking reactions initiate on the active sites of the catalysts with the formation of carbocations and the subsequent ionic chain reactions produce branched alkanes and aromatic compounds to constitute the crackate (cracked gasoline with high octane number), light olefins, cycle oils, and slurry oil that are sent to the fractionator. A carbon-rich byproduct of catalytic cracking, termed “coke,” deposits on catalyst surfaces and blocks the active sites. FCC is considered a carbon rejection process because the coke deposited on the catalyst surface and eventually burned off for heat is rich in carbon and thus enables the production of large quantities of a light distillate (crackate) in the process without the addition of hydrogen.
2ND EXPLANATION
Question 26 of 67
26. Question
1 points
Category: MATHEMATICS
The function f (x, y) = x² + y² – xy – x – y + 5 has the
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Question 27 of 67
27. Question
1 points
Category: MATHEMATICS
A fair die is rolled four times. Find the probability that six shows up twice
Correct
Incorrect
Question 28 of 67
28. Question
1 points
Category: PROCESS CALCULATIONS
A butane isomerization process produces 70 kmol/h of pure isobutane. A purge stream removed continuously contains 85% n butane and 15% impurity (mole %). The feed stream is n-butane containing 1% impurity (mole %). The flow rate of the purge stream will be
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Question 29 of 67
29. Question
1 points
Category: THERMODYNAMICS
The Maxwell relation derived from the differential expression for the Helmholtz free energy (dA) is :
Correct
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Question 30 of 67
30. Question
1 points
Category: THERMODYNAMICS
At 100ºC, water and methylcyclohexane both have vapour pressures of 1.0 atm. Also at 100ºC, the latent heats of vapourization of these compounds are 40.63 kJ/mol for water and 31.55 kJ/mol for methylcyclohexane. The vapour pressure of water at 150ºC is 4.69 atm. At 150ºC, the vapour pressure of methycyclohexane would be expected to be :
Correct
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Question 31 of 67
31. Question
2 points
Category: FLUID MECHANICS
A Bingham fluid of viscosity M = 10 Pa s, and yield stress τ0 = 10 k Pa, is sheared between flat parallel plates separated by a distance 10-³ m. The top plate is moving with a velocity of 1 m/s. The shear stress on the plate is
Correct
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Question 32 of 67
32. Question
2 points
Category: THERMODYNAMICS
Air enters an adiabatic compressor at 300 K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (y = Cp/Cv = 7/5) and the process to be reversible, is
Correct
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Question 33 of 67
33. Question
2 points
Category: MECHANICAL OPERATIONS
The energy required per unit mass to grind limestone particles of very large size to 100 Mm is 12.7 kWh/ton. An estimate (using Bond’s Law) of the energy to grind the particles from a very large size to 50 Mm is
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Question 34 of 67
34. Question
2 points
Category: HEAT TRANSFER
The Sieder-Tate correlation for heat transfer in turbulent flow in a pipe gives Nu ∝ Re^0.8, where Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer coefficient varies with pipe diameter (D) as
Correct
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Question 35 of 67
35. Question
2 points
Category: HEAT TRANSFER
The overall heat transfer coefficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m²K. The fouling factor after one year of operation is found to be hdo = 2000 W/m²K. The overall heat transfer coefficient at this time is
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Question 36 of 67
36. Question
2 points
Category: HEAT TRANSFER
The heat flux (from outside to inside) across an insulating wall with thermal conductivity k = 0.04 W/m K and thickness 0.16 m is 10 W/m². The temperature of the inside wall is –5ºC. The outside wall temperature is
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Question 37 of 67
37. Question
2 points
Category: FLUID MECHANICS
The interfacial area per unit volume of dispersion, in a gas – liquid contractor, for fractional hold-up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m²/m³)
Correct
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\
Incorrect
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\
Question 38 of 67
38. Question
2 points
Category: MASS TRANSFER
200 kg of solid (on dry basis) is subjected to a drying process for a period of 5000 s. The drying occurs in the constant rate period with the drying rate as Nc = 0.5 x 10-³ kg/m²s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m²/100 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid).
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Question 39 of 67
39. Question
2 points
Category: MASS TRANSFER
In a single stage extraction process, 10 kg of pure solvent S (containing no solute A) is mixed with 30 kg of feed F containing A at a mass fraction XF = 0.2. The mixture splits into an extract phase E and a raffinate phase R, containing A at XE = 0.5 and XR = 0.05 respectively. The total mass of the extract phase is (in kg).
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Question 40 of 67
40. Question
2 points
Category: CHEMICAL REACTION ENGINEERING
The mean conversion in the exit stream, for a second-order, liquid phase reaction in a non-ideal flow reactor is given by
Correct
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Incorrect
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Question 41 of 67
41. Question
2 points
Category: CHEMICAL REACTION ENGINEERING
For a vapor phase catalytic reaction (A + B → P) which follows the Rideal mechanism and the reaction step is rate controlling, the rate of reaction is given by (reaction step is irreversible, product also adsorbs)
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Question 42 of 67
42. Question
2 points
Category: CHEMICAL REACTION ENGINEERING
The first-order, gas phase reaction is conducted isothermally in batch mode. The rare of change of conversion with time is given by
Correct
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Question 43 of 67
43. Question
2 points
Category: PROCESS CONTROL
An ideal PID controller has the transfer function . The frequency at which the Magnitude Ratio of the controller is 1, is
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Question 44 of 67
44. Question
2 points
Category: PROCESS CONTROL
The block diagram of an integrating level process is given below. For unit step change in the set point Δhset = 1 with Δd = 0, the offset exhibited by the system is
Correct
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Question 45 of 67
45. Question
2 points
Category: PROCESS CONTROL
A second order system can be obtained by connecting two first order systems and in series. The damping ratio of the resultant second order system for the case τ1≠τ2 will be
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Question 46 of 67
46. Question
2 points
Category: ECONOMICS
An investment of Rs. 1000 is carrying at interest of 10% compounded quarterly. The value of the investment at the end of five years will be
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Question 47 of 67
47. Question
1 points
Category: ECONOMICS
P is the investment made on an equipment, S is its salvage value at n is the life of the equipment in years. The depreciation for the mth year by the Sum-of-Years-Digits method will be
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Question 48 of 67
48. Question
2 points
Category: PLANT DESIGN
In a cylindrical vessel subjected to internal pressure, the longitudinal stress σL, and the circumferential stress, σh, are related by
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Question 49 of 67
49. Question
2 points
Category: CHEMICAL TECHNOLOGY
In the converter of the contact process for the manufacture of H2SO4, the equilibrium conversion of SO2 —–(a)—— with increase in the temperature and —–(b)—— with increase in the mole ratio of SO2 to air.
Correct
Incorrect
Question 50 of 67
50. Question
2 points
Category: CHEMICAL TECHNOLOGY
For the hydrogenation of oils, —-(a)—- is commonly used as catallyst, and —-(b)—-is a catalyst poison.
Correct
Incorrect
Question 51 of 67
51. Question
2 points
Category: MATHEMATICS
The parametaric equation of a curve is where t is the parameter. (a) What type of conic (parabola, circle, ellipse, hyperbola) does the curve represent ? (b) Find the unit tangent to the curve at t = 1. (c) Find the unit normal to the curve at t = 1.
Correct
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Question 52 of 67
52. Question
0 points
Category: MATHEMATICS
Laplace transforms :
(a) Show that the Laplace transform of
(b) Show from (a) that :
(c) Show from (a) that :
w/s²+w²
Correct
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Question 53 of 67
53. Question
2 points
Category: PROCESS CALCULATIONS
The process schematic of a propane dehydrogenation plant is shown below. It is desired to set up a simplified version of the material balance for this plant. Assume that the only reaction is the dehydrogenation of propane to propylene there are no side reactions. The yield of propylene per pass is 30% (i.e., 30% of the propane entering the reactor is converted to propylene). Assume that the amount of carbon formed on the catalyst is negligible. The product flow rate (stream S5) is 50 kmol/h. Calcutta the flow rates of all the other streams. Notice that all streams except stream S, are pure.
Correct
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Question 54 of 67
54. Question
2 points
Category: THERMODYNAMICS
100 m³ of carbon dioxide initially at 423 K and 50 bar (50 x 105 Pa) is to be isothermally compressed in a frictionless piston and cylinder device to a final pressure of 300 bar (300 x 10^5 Pa). Assuming ideal gas behaviour (R = 8.314 x 10-² bar m³/kmol K).
(a) Write a general expression for the energy balance for the gas within the piston and cylinder device as the system, and define all the terms. (b) Calculate the volume of the compressed carbon dioxide gas at 300 bar (c) Calculate the work done to compress the carbon dioxide gas (d) Calculate the heat flow on compression
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Question 55 of 67
55. Question
2 points
Category: THERMODYNAMICS
Normal pentane is isomerized to isopentane and neopentane at 500 K and atmospheric pressure. Determine the equilibrium composition (mole %) of the three components. State any assumptions made. Consider the reactions to be :
Given Data : Equilibrium Constant for reaction (A) at 500 K, K1 = 3.519 Equilibrium Constant for reaction (B) at 500 K, K2 = 0.682
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=0.9995
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=0.9995
Question 56 of 67
56. Question
2 points
Category: FLUID MECHANICS
The inlet velocity of water (ρ = 1000 kg/m³) in a right-angled bend-reducer is V1 = 1 m/s, as shown below. The inlet diameter is D1 = 0.8 m and the outlet diameter is D2 = 0.4 m. The flow is turbulent and the velocity profiles at the inlet and outlet are flat (plug flow). Gravitational forces are negligible.
(a) Find the pressure drop (P1 – P2) across the bend assuming negligible friction losses. (b) If the actual pressure drop is (P1 – P2) = 8.25 kPa, find the friction loss factor (Kf) based on the velocity V1
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Question 57 of 67
57. Question
2 points
Category: FLUID MECHANICS
The volumetric flow rate during constant pressure filtration is
where V is the total volume of filtrate collected in time t, and Kc and qo are constants. (a) Integrate the above equation to obtain a relation between V and t (b) Make a sketch of t/V versus V from your results (c) Given V = 1.0 litre at t = 41.3s and V = 2.0 liter at t = 108.3s find Kc.
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Question 58 of 67
58. Question
2 points
Category: HEAT TRANSFER
A 200 W heater has a spherical casing of diameter 0.2 m. The heat transfer coefficient for conduction and convection from the casing to the ambient air is obtained from Nu = 2 + 0.6 Re½ Pr^1/3, with Re = 10^4 and Pr = 0.69. The temperature of the ambient air is 30ºC and the thermal conductivity of air is k = 0.02 W/m K.
(a) Find the heat flux from the surface at steady state (b) Find the steady state surface temperature of the casing (c) Find the temperature of the casing at steady state for stagnant air. Why is this situation physically infeasible?
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Question 59 of 67
59. Question
2 points
Category: HEAT TRANSFER
A 1-2 shell and tube heat exchanger has liquid (specific heat Cp) flowing at a mass flow rate min the tubes and saturated steam (temperature Ts) condensing on the shell side. (a) Carry out a differential energy balance on a single tube to show that
where T is the temperature of the liquid N is the number of tube in a pass, z is the distance along the tube, D is the inner diameter of the tubes and U is the overall heat transfer coefficient based on the inside surface area. (b) Obtain an expression for the temperature of the liquid at the exit of the heat exchanger, T2. The length of the tubes is L and liquid enters the heat exchanger at temperature T0.
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Question 60 of 67
60. Question
1 points
Category: HEAT TRANSFER
For a counter-current, multistage contact, show that if the driving force for solute transfer is constant for all trays, then the number of stages is given by
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Question 61 of 67
61. Question
2 points
Category: MASS TRANSFER
A sugary substance A is added to a pot of milk (initially containing no A) and stirred vigorously by a spoon so that the concentration of A, CA, is uniform everywhere. The mass transfer coefficient for the transfer of A into the liquid is ksl = 1 x 10^-4 m/s. Solid A is added in great excess compared to the saturation capacity of milk to dissolve A. Assume that the solid-liquid interfacial area stays constant throughout the dissolution process and is given by a = 1000 cm². Derive the expression for CA versus time, t. Find the time taken for CA/CA* = 0.95 . CA* = 5×10-2 kmol/m³; VL = 1000 cm³
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Question 62 of 67
62. Question
2 points
Category: CHEMICAL REACTION ENGINEERING
The concentration versus batch time date for a constant volume, isothermal batch reactor is given in the Table below. Assuming the reaction to first order in A, find the best value of k1 by least squares regression
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Question 63 of 67
63. Question
2 points
Category: CHEMICAL REACTION ENGINEERING
A CSTR and a PFR of equal volume V (each) are given for the conduct of a second-order, isothermal, liquid phase reaction. The reactors are to be arranged sequentially (in series). Find the values of the conversions for the two possible reactor arrangements. , k2 = 1 m³/kmol s, CAO = 0.1 kmol/m³s and τ= 5s (for volume V).
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Question 64 of 67
64. Question
2 points
Category: CHEMICAL REACTION ENGINEERING
Find the expression for the effectiveness factor of a catalyst pellet in the form of a thin slab such that the area of two opposite faces is much larger than the area of the other four faces. Material A can diffuse from both the large faces. Assume a first order reaction and isothermal, irreversible conditions. The two large faces are separated by a distance 2w, the effective diffusivity of A in the slab in DAe and the rte constant is denoted by k1.
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Question 65 of 67
65. Question
2 points
Category: HEAT TRANSFER
The hot junction of a thermocouple having time constant T min. initially at room temperature of 300C. At time t = 0 min., it is placed in a bath held at 1000C. The thermocouple is connected to a recorded which has fast dynamics. At t = 2 min., the hot junction is withdrawn from the bath and held in the air which is at 300C. From the recorded data, the value of dT/dt at t = 2+ min. is given to you. DT/dt = -2.50C/min. at t = 2 min. Is this data sufficient to calculate the time constant of the thermocouple? If so, suggest a procedure for calculation of the time constant τ.
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Question 66 of 67
66. Question
2 points
Category: PROCESS CONTROL
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Question 67 of 67
67. Question
1 points
Category: ECONOMICS
A plant designers has to choose between equipment 1 and equipment 2. Equipment 1 is made of special material and requires no maintenance. The cost of the equipment is Rs. 3,00,000, Equipment 2 is of a lower cost material and costs Rs. 1,50,000. For maintenance of equipment 2, a maintenance cost of Rs. 10,000 has to be paid at the end of each year. Life of equipment 2 is four years while that of equipment 1 is 8 years. Interest rate is 15% compounded annually. Calculate the present worth of investment to be made for each equipment and choose the option, which has the lower present worth. Equipment I has a salvage value of Rs. 30,000 while equipment 2 has no salvage value.