ChE Indiabix Calculations Flashcards
1
Q
In Joule’s experiment, an insulated container contains 20 kg of water initially at 25°C. It is stirred by an agitator, which is made to turn by a slowly falling body weighing 40 kg through a height of 4 m. The process is repeated 500 times. The acceleration due to gravity is 9.8 ms^-2. Neglecting the heat capacity of agitator, the temperature of water (in °C) is
- 40.5
- 34.4
- 26.8
- 25
A
- 34.4
2
Q
The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are
- (COP)R = (COP)HP = 0.6
- (COP)R = 2.5; (COP)HP = 1.5
- (COP)R = 1.5; (COP)HP = 2.5
- (COP)R = (COP)HP = 2.5
A
- (COP)R = 1.5; (COP)HP = 2.5
3
Q
Hot water (0.01 m^3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m^3/min) of density 800 kg/m^3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately
- 32
- 37
- 45
- 50
A
- 32
4
Q
The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K= 0.04 W/m.°K and thickness 0.16m is 10 W/m^2. The temperature of the inside wall is - 5°C. The outside wall temperature is
- 25°C
- 30°C
- 35°C
- 40°C
A
- 35°C
5
Q
It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is
- 3.06 x 10^5
- 6.12 x 10^5
- 7.24 x 10^5
- 9.08 x 10^5
A
- 3.06 x 10^5
6
Q
200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 x 10^-3 kg/m^2.s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m^2/1000 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid)
- 0.5
- 0.05
- 0.1
- 0.15
A
- 0.1
7
Q
The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m^2. The approximate surface temperature (K) is
(Stefan-Boltzman constant = 5.67x10^-8 W/m^2.K^4)
- 1000
- 727
- 800
- 1200
A
- 1000
8
Q
A multiple effect evaporator has a capacity to process 4000 kg of solid caustic soda per day, when it is concentrating from 10% to 25% solids. The water evaporated in kg per day is
- 6000
- 24000
- 60000
- 48000
A
- 24000
9
Q
A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m^2.K. The Biot number is
- 5.6
- 0.025
- 3.5
- 0.0035
A
- 0.025
10
Q
Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be
- 0.35
- 0.45
- 0.55
- 0.85
A
- 0.45
11
Q
An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is
- 4000
- 9000
- 4600
- 3000
A
4000
12
Q
Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer co-efficient is 3k/l. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade ?
- 35.5
- 43.75
- 81.25
- 48.25
A
81.25
13
Q
1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is
- 520
- 200
- 400
- 500
A
400
14
Q
A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is
- 555
- 55.5
- 0.55
- 0.15
A
0.15
15
Q
1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m2 and the overall heat transfer co-efficient to the liquid is 1500 W/m2.°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be
- 15 min
- 22 min
- 44 min
- 51 min
A
51 min
16
Q
A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions ? Assume that the conductive heat transfer co-efficient is infinitely large.
- 5 minutes
- 10 minutes
- 20 minutes
- 40 minutes
A
5 minutes
17
Q
A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time
- t = 283 s
- t = 356 s
- t = 400 s
- t = 800 s
A
t = 800 s
18
Q
Three material A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of __________ °C.
- 40
- 95
- 70
- 50
A
70
19
Q
Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212°F may be around __________ BTU.
- 180
- 970
- 3.97
- data insufficient, can’t be predicted
A
180
20
Q
A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of materialA is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C.
- 6
- 12
- 18
- 24
A
12
21
Q
Fresh orange juice contains 12% (by weight) solids and the rest water 90% of the fresh juice is sent to an evaporator to remove water and subsequently mixed with the remaining 10% of fresh juice. The resultant product contains 40% solids. The kg of water removed from 1 kg fresh juice is
- 0.4
- 0.5
- 0.6
- 0.7
A
0.7
22
Q
The left face of a one dimensional slab of thickness 0.2 m is maintained at 80°C and the right face is exposed to air at 30°C. The thermal conductivity of the slab is 1.2 W/m.K and the heat transfer co-efficient from the right face is 10 W/m2.K. At steady state, the temperature of the right face in °C is
- 77.2
- 71.2
- 63.8
- 48.7
A
48.7
23
Q
In a laboratory test run, the rate of drying was found to be 0.5 x 10^-3 kg/m^2.s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.08 on a dry basis. A tray dryer is used to dry 100 kg (dry basis) of the same material under identical conditions. The surface area of the material is 0.04 m^2/kg of dry solid. The time required (in seconds) to reduce the moisture content of the solids from 0.3 to 0.2 (dry basis) is
- 2000
- 4000
- 5000
- 6000
A
5000
24
Q
A cylinderical pressure vessel of volume 6 πm^3 has to be designed to withstand a maximum internal pressure of 10 atm. The allowable design stress of the material is 125N/mm^2 and corrosion allowance is 2 mm. The thickness of the vessel for a length/diameter ratio of 3 will be close to
- 5 mm
- 6 mm
- 8 mm
- 10 mm
A
10 mm
25
In a solution containing 0.30 Kg mole of solute and 600 kg of solvent, the molality is
* 0.50
* 0.60
* 2
* 1
* 0.50
26
It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%).
* 15 min
* 51 min
* 71 min
* 94 min
* 71 min
27
Compound A is extracted from a solution of A + B into a pure solvent S. A Co-current unit is used for the liquid-liquid extraction. The inlet rate of the solution containing A is 200 moles of B/hr.m2 and the solvent flow, rate is 400 moles of S/m2. hr. The equilibrium data is represented by Y = 3X2 , where Y is in moles of a A/moles of B and X is in moles A/moles of S. The maximum percentage extraction achieved in the unit is
* 25%
* 50%
* 70%
* 90%
* 50%
28
If the specific heats of a gas and a vapor are 0.2KJ/Kg.°K and 1.5 KJ/Kg.°K respectively, and the humidity is 0.01; the humid heat in KJ/°Kg. is
* 0.31
* 0.107
* 0.017
* 0.215
* 0.215
29
At equilibrium the concentration of water in vapour phase (C*)in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is
* 0.0
* 0.2
* 0.4
* 1.0
* 0.4
30
A 25 cm x 25 cm x 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m x 1m x 1cm flat sheet of the same material is to be dried from one side only.Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is
* 1000
* 1500
* 2000
* 2500
* 1000
31
A distillation column separates 10000 kg/hr of a benzene-toluene mixture as shown in the figure below :
In the figure xF, xD and xW represent the weight fraction of benzene in the feed, distillate and residue respectively. The reflux ratio is
* 0.5
* 0.6
* 1.0
* 2.0
0.6
32
According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (αAB = 2) does not change appreciably in the coloumn.
* 5
* 9
* 12
* 28
* 12
33
The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m^2/m^3)
* 500
* 1200
* 900
* 800
* 500
34
Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 x 10^-3 kg mole/m2.s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m^2 .s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is
* 5.6 x 10^-4
* 8.5 x 10^-4
* 5.6 x 10^-3
* 8.5 x 10^-3
* 8.5 x 10^-4
35
The wet and 'dry bulb temperature for a vapour-gas mixture are 25°C and 30°C respectively. If the mixture is heated to 45°C at constant pressure, the wet bulb temperature will be __________ °C.
* 25
* > 25
* < 25
* - 25
* > 25
36
H2S is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5 x. The bulk concentration of H2S has to be reduced from 0.05 to 0.001 mole fraction in the gas side. The height of the tower (in metres) corresponding to an operating line given by, y = 5x + 0.001 is
* 2.0
* 1.56
* 1.0
* 0.56
* 2.0
37
1 kg of a saturated aqueous solution of a highly soluble component A at 60°C is cooled to 25°C. The solubility limits of A are (0.6 kgA/kg water) at 60°C and (0.2 kgA/kg water) at 25°C. The amount in kg of the crystals formed is
* 0.4
* 0.25
* 0.2
* 0.175
* 0.2
38
A mixture of 10% C6H6 vapour in air at 25°C and 750 mm Hg has a dew point of 20°C. Its dew point at 30°C and 700 mm Hg will be around __________ °C.
* 21.7
* 20
* 27.3
* 18.7
* 18.7
39
Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout).For 98% recovery of acetone, the number of trays required is/are
* 1
* 8
* 9
* 10
* 9
40
An alkaline solution is used to reduce the concentration of carbon dioxide in a stream from 10% to 0.1% by absorption with irreversible chemical reaction. The overall number of transfer units based on gas phase is
* 9.21
* 4.605
* 100
* 0.001
* 4.605
41
An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively.The humidity of air sample expressed as kg of water vapour/kg of dry air is
* 0.048
* 0.079
* 0.122
* 0.152
* 0.152
42
A pure drug is administered as a sphere and as a cube. The amount of drug is the same in the two tablets. Assuming that the shape and size do not influence the mass transfer, the ratio of rate of dissolution in water at t = 0 for the cubic to spherical tablet is
* 0.54
* 1.04
* 1.24
* 1.94
* 1.24
43
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 raf-finate phase R containing A at xB = 0.5 and xR = 0.05 respectively. The total mass of the extract phase is (in Kg)
* 6.89
* 8.89
* 10
* 8.25
* 8.89
44
Keeping the pressure constant, to double the volume of a given mass of an ideal gas at 27°C, the temperature should be raised to __________ °C.
* 270
* 327
* 300
* 540
* 327
45
If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.
100
50
205
200
200
46
Grams of butane (C₄H₁₀) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
* 580
* 640
* 1160
* data insufficient; can't be computed
* 1160
47
A solid metallic block weighing 5 kg has an initial temperature of 500°C. 40 kg of water initially at 25°C is contained in a perfectly insulated tank. The metallic block is brought into contact with water. Both of them come to equilibrium. Specific heat of block material is 0.4 kJ.kg-1. K-1. Ignoring the effect of expansion and contraction and also the heat capacity to tank, the total entropy change in kJ.kg-1 , K-1 is
* -1.87
* 0
* 1.26
* 3.91
* 0
48
A gas has a volume of 27.3 c.c. at 0°C. Its volume at 10°C (if pressure remains unchanged) will be __________ c.c.
* 2.73
* 28.3
* 273
* 283
* 28.3
49
A cyclic engine exchanges heat with two reservoirs maintained at 100 and 300°C respectively. The maximum work (in J) that can be obtained from 1000 J of heat extracted from the hot reservoir is
* 349
* 651
* 667
* 1000
* 349
50
The following heat engine produces power of 100000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is
* 100, 000 kW
* 160, 000 kW
* 200, 000 kW
* 320, 000 kW
* 320, 000 kW
51
For water at 300°C, it has a vapour pressure 8592.7 kPa and fugacity 6738.9 kPa Under these conditions, one mole of water in liquid phase has a volume of 25.28 cm3 and that in vapour phase in 391.1 cm3.Fugacity of water (in kPa) at 9000 kPa will be
* 6738.9
* 6753.5
* 7058.3
* 9000
* 6753.5
52
In vapour compression refrigeration system, if the evaporator temperature and the condenser temperatures are -13°C and 37°C respetively, the Carnot COP will be
* 5.2
* 6.2
* 0.168
* data insufficient, can't be found out
* 5.2
53
COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
* 0.5
* 3.5
* 4.5
* 8.5
* 3.5
54
4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is
* 4 J
* ∞
* 0
* 8 J
* 0
55
A cylinder contains 640 gm of liquid oxygen. The volume occupied (in litres) by the oxygen, when it is released and brought to standard conditions (0°C, 760 mm Hg) will be __________ litres.
* 448
* 224
* 22.4
* data insufficient; can't be computed
* 448
56
Air enters an adiabatic compressor at 300K. 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
* 300(3^2/7)
* 300(3^3/5)
* 300(33^3/7)
* 300(3^5/7)
* 300(3^2/7)
57
One ton of refrigeration capacity is equivalent to the heat removal rate of
* 50 k cal/hr
* 200 BTU/hr
* 200 BTU/minute
* 200 BTU/day
* 200 BTU/minute
58
1m^3 of an ideal gas at 500 K and 1000 kPa expands reversibly to 5 times its initial volume in an insulated container. If the specific heat capacity (at constant pressure) of the gas is 21 J/mole . K, the final temperature will be
* 35 K
* 174 K
* 274 K
* 154 K
* 274 K
59
One mole of nitrogen at 8 bar and 600 K is contained in a piston-cylinder arrangement. It is brought to 1 bar isothermally against a resisting pressure of 1 bar. The work done (in Joules) by the gas is
* 30554
* 10373
* 4988.4
* 4364.9
* 10373
60
If heat contents of CH₄, C₂H₄ and C₃H₈ are -17.9, 12.5 and -24.8 kcal/mole respectively, than ΔH for the reaction CH₄(g) + C₂H₄(g) ⇌ C₃H₈(g) will be __________ Kcal.
* -19.4
* -30.2
* 55.2
* -55.2
* -19.4
61
At 60° C, vapour pressure of methanol and water are 84.562 kPa and 19.953 kPa respectively. An aqueous solution of methanol at 60° C exerts a pressure of 39.223 kPa; the liquid phase and vapour phase mole fractions of methanol are 0.1686 and 0.5714 respectively. Activity co-efficient of methanol is
* 1.572
* 1.9398
* 3.389
* 4.238
* 1.572
62
In the reaction, C + O2 → CO2 ; ΔH = - 94 kcal. What is the heat content (enthalpy)of O2?
* -94 kcal
* > -94 kcal
* < - 94 kcal
* zero
* zero
63
The drag co-efficient for a bacterium moving in water at 1 mm/s, will be of the following order of magnitude (assume size of the bacterium to be 1 micron and kinematic viscosity of water to be 10⁻⁶m²/s).
* 24000
* 24
* 0.24
* 0.44
* 0.44
64
A Bingham fluid of viscosity μ = 10 Pa.s and yield stress, τ₀ = 10 KPa, is shared between flat parallel plates separated by a distance of 10⁻³ m. The top plate is moving with a velocity of 1 m/s. The shear stress on the plate is
* 10 KPa
* 20 KPa
* 30 KPa
* 40 KPa
* 20 KPa
65
A mercury (specific gravity = 13.6) manometer connected across an orificemeter fitted in a pipe shows a manometer reading of 2 cms. If the manometer liquid is changed to carbon tetrachloride (specific gravity = 1.6), then for the same flow rate of water the new manometer reading will be __________ cms.
* 17
* 42
* 84
* 1.8
* 17
66
A centrifugal pump has the following specifications:
Power = 4 H.P.; Speed = 800 rpm
Head = 8 metres
Flow = 1000 litres/minutes.
If its speed is halved, the new discharge will be __________ litres/minute.
* 500
* 200
* 1000
* 750
* 500
67
A pipe of I.D. 4 m is bifurcated into two pipes of I.D. 2 m each. If the average velocity of water flowing through the main pipe is 5 m/sec, the average velocity through the bifurcated pipes is
* 20 m/sec
* 10 m/sec
* 5√2 m/sec
* 5 m/sec
* 10 m/sec
68
A centrifugal pump is used to pump water through a horizontal distance of 150 m, and then raised to an overhead tank 10 m above. The pipe is smooth with an I.D of 50 mm. What head (m of water) must the pump generate at its exit (E) to deliver water at a flow rate of 0.001 m3/s? The Fanning friction factor, f is 0.0062.
* 10 m
* 11 m
* 12 m
* 20 m
* 11 m
69
The peripherial velocity at inlet of a centrifugal pump having inlet diameter of 25 cms and rotating at 950 rpm is __________ m/sec.
* 1.8
* 12.4
* 186.2
* 736.4
* 12.4
70
The fluid jet discharging from a 2" diameter orifice has a diameter of 1.75" at its vena-contracta. The co-efficient of contraction is
* 1.3
* 0.766
* 0.87
* none of these
* 0.766
71
A bed consists of particles of density 2000 kg/m³. If the height of the bed is 1.5 metres and its porosity 0.6, the pressure drop required to fluidise the bed by air is
* 25.61 kPa
* 11.77 kPa
* 14.86 kPa
* 21.13 kPa
* 11.77 kPa
72
A gas (density = 1.5 kg/m12600 Pa/m³ , viscosity = 2x 10⁻⁵ kg/m.s) flowing through a packed bed (particle size = 0.5 cm, porosity = 0.5) at a superficial velocity of 2 m/s causes a pressure drop of 8400 Pa/m. The pressure drop for another gas, with density of 1.5kg/m³ and viscosity of 3 x 10⁻⁵ kg/m.s flowing at 3 m/s will be
* 8400 Pa/m
* 12600 Pa/m
* 18900 Pa/m
* 16800 Pa/m
* 12600 Pa/m
73
What is the co-efficient of contraction, if a fluid jet discharging from a 50 mm diameter orifice has a 40 mm diameter at its vena-contracta ?
* 0.64
* 1.65
* 0.32
* 0.94
* 0.64
74
A Pitot tube indicates 5 cm of water (manometer) when it is being used for measuring velocity of air. The velocity of air in m/sec is
* 5
* 14.1
* 56.22
* 28.2
* 28.2
75
A liquid is pumped at the rate of 600 litres using 1000 rpm. If the rpm is changed to 1100, the liquid pumped is __________ litres.
* 600
* 660
* 1.1
* 60
* 660
76
A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun's equation for the above fluid-particle system (in SI units) is given below :
Δ P/L = 375 x 10³ VOM + 10.94 x 10⁶ VOM² (SI units)
If water is to be used as the fluidising medium, in actual operation, the above bed has a height = 1 m. What is the porosity of the fluidised bed ?
* 0.2
* 0.5
* 0.7
* 0.8
* 0.7
77
A centrifugal pump has the following specifications:
Power = 4 H.P.; Speed = 800 rpm
Head = 8 metres
Flow = 1000 litres/minutes.
If its speed is halved, then the new head will be __________ metres.
* 2
* 4
* 8
* 5.5
* 2
78
Water is flowing at 1 m/sec through a pipe (of 10 cm I.D) with a right angle bend. The force in Newtons exerted on the bend by water is
* 10√ (2π)
* 5π/2
* 5√ (2π)
* 5π/√ 2
* 5π/2
79
A hydraulic press has a ram of 10 cms in diameter and a plunger of 1 cm in diameter. The force required on the plunger to raise a weight of 10 tons on the ram is __________ kg.
* 10
* 100
* 1000
* 10000
* 100
80
A centrifugal pump has the following specifications:
Power = 4 H.P.; Speed = 800 rpm
Head = 8 metres
Flow = 1000 litres/minutes.
If its speed is halved, the power consumed now will be __________ hp.
* 0.5
* 2
* 4
* 1
* 0.5
81
Bed pressure drop in an air fluidised bed of catalyst particles (ρp = 200 kg/m3, Dp = 0.05 cm) of 60 cm bed depth and bed porosity of 0.5 expressed in cm of water (manometer) is
* 90
* 60
* 45
* 30
* 60
82
A fluidis (μ/ρ = 0.01 cm²/sec) is moving at critical flow condition (NRe = 2100) through a pipe of dia 3 cms. Velocity of flow is __________ cm/sec.
* 7
* 700
* 7000
* 630
* 7
83
A rotameter through which air at room temperature and atmospheric pressure is flowing gives a certain reading for a flow rate of 100 cc/sec. If helium (molecular weight 4) is used and rotameter shows the same reading, the flow rate (cc/sec) is
* 26
* 42
* 269
* 325
* 269
84
A 0.5 m high bed made up of a 1 mm dia glass sphere (density 2500 kg/m³ ) is to be fluidised by water (density 1000 kg/m³ ). If at the point of incipient fluidisation, the bed voidage is 40%, the pressure drop across the bed is
* 4.4 KPa
* 2.94 KPa
* 3.7 KPa
* none of these
* 4.4 KPa
85
A rectangular surface 3' x 4', has the lower 3 edge horizontal and 6' below a free oil surface (sp. gr. 0.8). The surface inclination is 300 with the horizontal. The force on one side of the surface is(where, y = specific weight of water)
* 39.6y
* 48y
* 49.2y
* 58y
* 48y
86
A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun's equation for the above fluid-particle system (in SI units) is given below :
Δ P/L = 375 x 10³ VOM + 10.94 x 10⁶ VOM² (SI units)
If water is to be used as the fluidising medium, the minimum fluidisation velocity, VOM is
* 12 mm/s
* 16 mm/s
* 24 mm/s
* 28 mm/s
* 16 mm/s
87
The energy required per unit mass to grind limestone particles of very large size to 100 μm 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 μm is
* 6.35 kWh/ton
* 9.0 kWh/ton
* 18 kWh/ton
* 25.4 kWh/ton
* 18 kWh/ton
88
The sphericity of a cylinder of 1 mm diameter and length 3 mm is
* 0.9
* 0.78
* 0.6
* 0.5
* 0.9
89
Pulverised coal passing through 200 mesh screen has a diameter of 0.074 mm (74 micron). The same passing through 50 mesh screen will have a dia of __________ mm.
* 0.007
* 0.30
* 50
* 0.014
* 0.30
90
A suspension of glass beads in ethylene glycol has a hindered settling velocity of 1.7 mm/s, while the terminal settling velocity of a single glass bead in ethylene glycol is 17 mm/s. If the Richardson-Zaki hindered settling index is 4.5, the volume fraction of solids in the suspension is
* 0.1
* 0.4
* 0.6
* none of these
* 0.6
91
For a cyclone of diameter 0.2 m with a tangential velocity of 15 m/s at the wall, the separation factor is
* 2250
* 1125
* 460
* 230
* 230
92
What is the critical rotation speed in revolutions per second, for a ball mill of 1.2 m diameter charged with 70 mm dia balls ?
* 0.5
* 1.0
* 2.76
* 0.66
* 0.66
93
Work index is the gross energy (kWh/tonne of feed) necessary to reduce a very large feed to such a size that 80% of product particles will pass through a 0.1 mm screen. The value of work index determined for wet grinding should be multiplied with __________ to get the same for dry grinding.
* 1.0
* 0.5
* 1.34
* 4.34
* 1.34
94
The basic filtration equation is given as dt/dV = μ/A·ΔP [(α·CV/A) + Rm] where, V is volume of the filtrate ; A is the filtration area, a is specific cake resistance, μ is viscosity of the filtrate, and Cis the concentration of the solids in the feed slurry.
In a 20 minutes constant rate filtration, 5 m^3 of filtrate was obtained. If this is followed by a constant pressure filtration, how much more time in minutes, it will take for another 5 m3 of filtrate to be produced ? Neglect filter medium resistance, Rm ; assume incompressible cake.
* 10
* 20
* 25
* 30
* 20
95
A sand mixture was screened through a standard 10-mesh screen. The mass fraction of the oversize material in feed, overflow and underflow were found to be 0.38, 0.79 and 0.22 respectively. The screen effectiveness based on the oversize is
* 0.50
* 0.58
* 0.68
* 0.62
* 0.50
96
What is the reduction ratio in a fine crushing operation having following feed and product sizes?
Parameters Max Min
feed size 20 10
product size 10 5
* 0.5
* 2
* 5
* 10
* 2
97
What is the order of a chemical reaction, A + 2B K→ C , if the rate of formation of 'C', increases by a factor of 2.82 on doubling the concentration of 'A' and increases by a factor of 9 on trebling the concentration of 'B'?
* 7/2
* 7/4
* 5/2
* 5/4
* 7/2
98
For every 10°C rise in temperature, the rate of chemical reaction doubles. When the temperature is increased from 30 to 70°C, the rate of reaction increases __________ times.
* 8
* 12
* 16
* 32
* 16
99
6 gm of carbon is burnt with an amount of air containing 18 gm oxygen. The product contains 16.5 gms CO2 and 2.8 gms CO besides other constituents. What is the degree of conversion on the basis of disappearance of limiting reactant ?
* 100%
* 95%
* 75%
* 20%
* 95%
100
The rate constant of a chemical reaction increases by 100 times when the temperature is increased from 400 °K to 500 °K. Assuming transition state theory is valid, the value of E/R is
* 8987°K
* 9210°K
* 8764°K
* 8621°K
* 9210°K
101
At a given value of E/R (ratio of activation energy and gas constant), the ratio of the rate constants at 500°K and 400°K is 2, if Arrhenious law is used. What will be this ratio, if transition state theory is used with the same value of E/R?
* 1.6
* 2
* 2.24
* 2.5
* 2.5
102
Rate constant for a first order reaction does not depend upon reaction time, extent of reaction and the initial concentration of reactants ; but it is a function of reaction temperature. In a chemical reaction, the time required to reduce the concentration of reactant from 100 gm moles/litre to 50 gm moles/litre is same as that required to reduce it from 2 gm moles/litre to 1 gm mole/litre in the same volume. Then the order of this reaction is
* 0
* 1
* 2
* 3
* 1
103
The rate of a chemical reaction is almost doubled for every 10°C rise in temperature. The rate will increase __________ times, if the temperature rises form 10 to 100°C.
* 256
* 512
* 112
* 612
* 512
104
For the liquid phase zero order irreversible reaction A B, the conversion of A in a CSTR is found to be 0.3 at a space velocity of 0.1min-1 . What will be the conversion for a PFR with a space velocity of 0.2 min-1? Assume that all the other operating conditions are the same for CSTR and PFR.
* 0.15
* 0.30
* 0.60
* 0.90
* 0.60
105
Three plug flow reactors (PFR's) of 4, 5 & 6 m3 volumes are arranged in two branches as shown below in the figure.
(image S3P4)
If the total feed rate is 300 tons/hr, then for the same conversion in each branch, the feed rate through branch II should be __________ tons/hr.
* 100
* 150
* 200
* 225
* 100
106
A chemical reaction, A → 3B, is conducted in a constant pressure vessel. Starting with pure A, the volume of the reaction mixture increases 3 times in 6 minutes. The fractional conversion is
* 0.33
* 0.5
* 1
* data insufficient, can't be predicted
* 1
107
Given,
3H2 + CO = CH4 + H2O, KP = 10^1.84 and,
4H2 + CO2 = CH4 + 2H2O, KP = 10^1.17
the KP for the reaction CO + H2O = CO2 + H2 is
* 10^3.01
* 10^-0.67
* 10^-3.01
* 10^0.67
* 10^-0.67
108
A batch adiabatic reactor at an initial temperature of 373°K is being used for the reaction, A → B. Assume the heat of reaction is - 1kJ/mole at 373°K and heat capacity of both A and B to be constant and equal to 50J/mole.K. The temperature rise after a conversion of 0.5 will be
* 5°C
* 10°C
* 20°C
* 100°C
* 10°C
109
Pure ethanol vapor is fed to a reactor packed with alumina catalyst, at the rate of 100 kmole / hr. The reactor products comprise: ethylene :95 kmole / hr, water vapour: 97.5 k mole / hr and diethyl ether :2.5 kmole/hr. The reactions occuring can be represented by:
C2H5OH C2H4 + H2O
2C2H5OH C2H5 - O - C2H5 + H2O
The percent conversion of ethanol in the reactor is
* 100
* 97.5
* 95
* 2.5
* 100
110
The reaction A B is conducted in an adiabatic plug flow reactor (PFR). Pure A at a concentration of 2 kmol/m3 is fed to the reactor at the rate of 0.01 m3 /s and at a temperature of 500 K. If the exit conversion is 20%, then the exit temperature (in k)is (Data: Heat of reaction at 298 K = - 50000 kJ/ kmole of A reacted Heat capacities CPA = CPB = 100kJ/kmole. K (may be assumed to be independent of temperature))
* 400
* 500
* 600
* 1000
* 600
111
A CSTR is to be designed in which an exothermic liquid phase first order reaction of the type, A → R, is taking place. The reactor is to be provided with a jacket in which coolant is flowing. Following data is given: CA0= 5 kmole/m^3 ; XA = 0.5; Feed temperature = reactor temperature = 40°C. Rate constant at 40°C = 1 min-1 ; (ΔH) = - 40kJ/mole; ρ = 1000kg/m3 CP = 4 J/gm.°C ; q = 10^-3 m^3/min (ρ and CP are same for the reactant and product streams). The amount of heat to be removed is
* 2/3 kW
* 1kW
* 5/3 kW
* 4kW
* 5/3 kW
112
For an isothermal second order aqueous phase reaction, A B, the ratio of the time required for 90% conversion to the time required for 45% conversion is
* 2
* 4
* 11
* 22
* 11
113
Second order consecutive irreversible reactions A --(k1)> B--(k2)> C were carried out in a constant volume isothermal batch reactor with different initial feed compositions. Reactor temperature was same in all the cases. In experiments where the ratio of concentration of B to that of A in the initial feed was less than 0.5, the concentration of B increased first, reached a maximum and then declined with time. However, for all experiments where this concentration ratio was 0.5 or above, concentration of B decreased monotonically with time right from the beginning. What is the ratio of the two rate constants (k1/k2)?
* 1/4
* 1/2
* 2
* 4
* 1/4
114
An isothermal aqueous phase reversible reaction, P ⇌ R, is to be carried out in a mixed flow reactor. The reaction rate in k.mole/m^3 .h is given by, r = 0.5CP - 0.125CR. A stream containing only P enters the reactor. The residence time required (in hours) for 40% conversion of P is
* 0.80
* 1.33
* 1.60
* 2.67
* 1.60
115
For the reaction 2X + Y --K-> Z, the rate of formation of Z is 0.2 gm mole/litre.hr. what is the rate of disappearance of X in gm mole/litre. hr ?
* 0.4
* 0.1
* 0.2
* none ofthese
* 0.4
116
An irreversible aqueous phase reaction, A + B → P, is carried out in an adiabatic mixed flow reactor. A feed containing 4kmole/m3 of each A and B enters the reactor at 8m3 /hr. If the temperature of the exit stream is never to exceed 390 K, what is the maximum inlet feed temperature allowed?
Data: Heat of reaction = - 50 kJ/mole
Density of the reacting mixture = 1000kg/m3
Specific heat of reacting mixture = 2kJ/kg.K
The above data can be assumed to be independent of temperature and composition.
* 190
* 290
* 390
* 490
* 290
117
Half life period of decomposition of a liquid 'A' by irreversible first order reaction is 12 minutes. The time required for 75% conversion of 'A' is __________ minutes.
* 18
* 24
* 6
* 12
* 24
118
The conversion in a mixed reactor/accomplishing a reaction A 3R is 50% when gaseous reactant 'A' is introduced at the rate of 1 litre/second and the leaving flow rate is 2 litres/second. The holding time for this operation is __________ second.
* 0.5
* 1
* 2
* 3
* 0.5
119
For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to
* 1
* 0.5
* 0.1
* 0
* 0.1
120
For the reversible reaction A ⇌ 2B, if the equilibrium constant K is 0.05 mole/litre; starting from initially 2 moles of A and zero moles of B, how many moles will be formed at equilibrium ?
* 0.253
* 0.338
* 0.152
* 0.637
* 0.338
121
Time required for 50% decomposition of a liquid in an isothermal batch reactor following first order kinetics is 2 minutes. The time required for 75% decomposition will be about __________ minutes.
* 3
* 4
* 6
* 8
* 4
122
Pure A in gas phase enters a reactor 50% of this A is converted to B through the reaction, A 3B. Mole fraction of A in the exit stream is
* 1/2
* 1/3
* 1/4
* 1/5
* 1/3
123
The following gas phase reactions are carried out isothermally in a CSTR.
A → 2R ; r1 = k1pA ;
k1 = 20mole/(sec.m^3 bar)
A → 3S ; r2 = k2 pA ;
k2 = 40mole/(sec.m^3 .bar)
What is the maximum possible value of FR(mole/sec.) ?
* 1/3
* 1/2
* 2/3
* 2
* 2/3
124
The gas phase reaction 2A B is carried out in an isothermal plug flow reactor. The feed consists of 80 mole % A and 20 mole % inerts. If the conversion of A at the reactor exit is 50%, then CA/CA0 at the outlet of the reactor is
* 2/3
* 5/8
* 1/3
* 3/8
* 5/8
125
The following half life data are available for the irreversible liquid phase reaction A products.
Initial Concentration 2 8
(K.mol/m^3)
Half Life 2 1
The overall order of reaction is
* 0.5
* 1
* 1.5
* 2
* 1.5
126
For the gaseous reaction 2A B, where the feed consists of 50 mole % A and 50 mole % inerts, the expansion factor is
* 1
* -0.5
* -0.25
* 0
* -0.25
127
A pollutant P degrades according to first order kinetics. An aqueous stream containing P at 2 kmole/m^3 and volumetric flow rate 1m^3 /h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmole/m^3 . The inlet concentration of the pollutant is now doubled and the volumetric flow rate is tripled. If the pollutant level is to be brought down to the same level of 0.5 kmole/m^3 , the volume of the mixed flow reactor should be increased by a factor of
* 7
* 6
* 3
* 7/3
* 7
128
A gaseous reactant is introduced in a mixed reactor of 3 litres volume at the rate of 1 litre/second. The space time is __________ seconds.
* 1
* 3
* 1/3
* 32
* 3
129
A liquid decomposes by irreversible first order kinetics and the half life period of this reaction is 8 minutes. The time required for 75% conversion of the liquid will be __________ minutes.
* 4
* 8
* 12
* 16
* 16
130
The conversion for a first order liquid phase reaction. A → B in a CSTR is 50%. If another CSTR of the same volume is connected in series, then the % conversion at the exit of the second reactor will be
* 60
* 75
* 90
* 100
* 75
131
In the hydrodealkylation of toluene to benzene, the following reactions occur:
C7H8 + H2 → C6H6 + CH4
2C6H6 ⇌ C12H10 + H2
Toluene and hydrogen are fed to a reactor in a molar ratio 1:5.80% of the toluene gets converted and the selectivity of benzene(defined as moles of benzene formed/moles of toluene converted) is 90%. The fractional conversion of hydrogen is
* 0.16
* 0.144
* 0.152
* 0.136
* 0.144
132
The conversion of a reactant, undergoing a first order reaction, at a time equal to three times the half life of the reaction is
* 0.875
* 0.5
* 0.425
* data insufficient to calculate
* 0.875
133
An enzyme is assayed at an initial substrate concentration of 2 x 10⁻⁵ M. In 6 minute, half of the substrate is used. The Km for the substrate is 2 x 10⁻³ M. The value of k in minute is
* 0.115
* 0.42
* 0.093
* 6.693
* 0.115
134
For an enzyme that displays Michaelis-Menten kinetics, the reaction velocity (as a fraction of Vmax) observed at [S] = 2 KM will be
* 0.09
* 0.33
* 0.66
* 0.91
* 0.66
135
An enzyme has a Km of 4.7 x 10-5M. If the Vmax of the preparation is 22m moles liter-1 min-1, what velocity would be observed in the presence of 2.0 x 10-4M substrate and 5.0 x 10-5M of a competitive inhibitor?
* 13.54μ moles liter-1min-1
* 6.68μ moles liter-1min-1
* 7.57μ moles liter-1min-1
* 17.8μ moles liter-1min-1
* 13.54μ moles liter-1min-1
136
When [S] = 0.1 *KM, the velocity of an enzyme catalyzed reaction is about:
* 0.1 * Vmax
* 0.3 * Vmax
* 0.5 * Vmax
* 0.7 * Vmax
* 0.1 * Vmax
137
