chemical engineering Mcqs
3551. Lap joints are preferred for plates having thickness _______________ mm?
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A. 10-May

B. > 3

C. > 5

D. < 12.5

3552. An increase in the liquid resistance to interphase mass transfer and a resultant reduction in plate efficiency is caused by______________?
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A. All A., B. and C.

B. Decrease in gas solubility for absorbers

C. An increase in liquid viscosity

D. An increase in relative volatility for rectification columns

3553. In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about _______________ cms?
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A. 10

B. 20

C. 30

D. 35

3554. The longitudinal stress induced in a thin walled cylindrical vessel under internal pressure is_________________?
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A. pd/2t

B. pd/4t

C. pd/8t

D. pd/t

3555. Filtration rate is affected by the________________?
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A. Pressure drop across the cake & filter medium

B. All A., B. and C.

C. Cake & filter medium resistance

D. Area of filtering surface & the viscosity of filtrate

3556. Nominal size of a pipe is an indication of its _______________ diameter?
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A. None of these

B. Outer

C. Approximate

D. Inner

3557. Hazards associated with the relief valve leakage for extremely hazardous material storage can be taken care of by providing___________________?
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A. Rupture diaphragm

B. Dikes

C. Surge chamber

D. None of these

3558. Tube side pressure drop in a 1-2 heat exchanger (for turbulent flow of fluids through the tubes) is about __________ times, that in a 1-1 heat exchanger having the same size & number of tubes and operated at the same liquid flow rate ?
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A. 8

B. 4

D. 2

3559. For identical operating conditions, the pressure drop over _______________ tray is the highest out of the following?
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A. Valve

B. Bubble cap

C. Counter flow

D. Sieve

3560. Wind load consideration in the design of a support can be neglected, when the vessel is___________________?
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A. None of these

B. Tall but empty

C. Short (< 2 m) and housed indoor

D. Tall (say 30 metres), but is full of liquid

3561. In case of saddle packing (e.g., berl and intralox saddles), the maximum size of the packing should not exceed ______________ of the column diameter?
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A. 1/15th

B. 1/50th

C. 1/5th

D. 1/30th

3562. Cooling water fouling factors vary in the range of 0.001 to 0.003____________________?
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A. (W/m2.K)-1

B. (BTU/hr.ft2. F)-1

C. (kcal/hr. m. C)-1

D. (kcal/hr.m2.C)-1

3563. A stuffing box is used for____________________?
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A. Prevention of fluid leakage around moving parts

B. Reducing the resistance of fluid flow

C. Absorbing the contraction/expansion of pipeline due to temperature changes

D. Facilitating smooth opening and closing of a valve

3564. Optimum reflux ratio in a continuous distillation column is determined by the__________________?
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A. Total cost consideration (fixed cost of the column plus the cooling water & steam cost)

B. Maximum permissible vapour velocity

C. Flooding limit of the column

D. None of these

3565. (Le/D) for fully open globe value may be around__________________?
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A. 25

B. 10

C. 300

D. 75

3566. The testing pressure of storage tanks and pressure vessels designed as per Indian standard codes should be about ______________ times the design pressure?
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A. 3 to 4

B. 1.5 to 2

C. 4 to 5

D. > 5

3567. Poissons ratio of a material is the ratio of unit lateral strain to the unit axial elongation within its elastic limit. The value of Poissons ratio for structural and pressure vessel steel may be taken as ____________________?
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A. 0.01

B. 0.3

C. 0.95

D. 0.75

3568. The minimum tray spacing in distillation column of diameter less than 3 ft is normally _____________ inches?
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A. 18

B. 34

C. 24

D. 6
3569. 25 per cent cut segmental baffle means that the baffle__________________?
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A. Height is 75% of the I.D. of the shell

B. Width is 25% of its height

C. Height is 25% of the I.D. of the shell

D. Spacing is 75% of its height

3570. In case of design of a shell and tube heat exchanger___________________?
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A. All A., B. & C.

B. mm tube diameter; and for > 15 mm tube diameter, tube sheet thickness is smaller than

C. O.D. of the tube is 6 to 40 mm while the tube lengths used are 0.5, 2.5, 3.0, 4.0, 5.0, 6 metres

D. Minimum tube sheet thickness (in which tubes are fixed) is equal to the O.D. of the tube upto

E. Minimum cleaning lane of 6.5 mm is provided, when tubes are on a square pitch

F. e diameter

3571. In hydrostatic testing of welded pipe (for leakage, strength etc.) the ratio of minimum hydrostatic test pressure to internal design pressure is around __________________?
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A. 1.5

B. 3.5

C. 0.5

D. 2.5

3572. An under-designed steam trap will___________________?
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A. Waste steam

B. Back up condensate and cause water hammer in steam line

C. Destroy itself of acceleration wear due to rapid recycling

D. None of these

3573. Circumferential (hoop) stress in a thin cylindrical vessel under internal pressure is _____________ the longitudinal stress?
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A. Eight times

B. Twice

C. Equal to

D. Half

3574. Most of the storage vessels/tanks are made cylindrical, because of the fact that a cylinder _________________?
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A. Has greater structural strength

B. Is easy to fabricate

C. Both A. and B.

D. Neither A. nor B.

3575. In a shell and tube heat exchanger, the clearance of the tube is generally___________________?
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A. Equal to the tube diameter

B. More in case of triangular pitch as compared to the square pitch tube layout

C. More than the tube diameter

D. Not less than one-fourth of the tube diameter or 3/16?
3576. In a _____________ riveted joint, the number of rivets decreases from the innermost row to the outermost row?
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A. Zig-zag

B. Diamond

C. None of these

D. Chain

3577. The ratio of tube length to shell diameter in case of liquid shell and tube heat exchanger ranges from__________________?
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A. 4 to 8

B. 6 to 12

C. 3 to 5

D. 2 to 3

3578. _____________ shaped roof is the most commonly used roof for cylindrical storage tanks?
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A. Conical

B. Dome

C. Umbrella

D. Flat

3579. Value of Peclet number = 0, is the representative of ____________________?
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A. Eddy diffusivity = 0

B. Laminar flow

C. Complete back mixing

D. Plug flow

3580. Accidents in chemical plants are mostly due to___________________?
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A. Improper layout of the equipments

B. Failure of equipments

C. Faulty operating procedures

D. Inadequate equipment design

3581. Friction factor for turbulent flow in a new pipe is given by____________________?
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B. f = 16/NRe

C. f = 0.04/(NRe)0.16

D. f = 0.22 NRe

E. f = 25/NRe

3582. In a rotary drier, the average retention time of solid is (where Z = length of the drier, metres ? = apparent solid density, kg/m3 L = flow rate of dry solids, kg/see. m2 drier crosssection H = hold up of solid.) ?
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A. Z.H.?/L

B. Z.H/?L

C. L/Z.H.?

D. H.?/L

3583. The stress developed in a material without any permanent set is called the____________________?
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A. Elastic limit

B. Yield stress

C. Breaking stress

D. Ultimate stress

3584. A riveted joint does not fail by _____________________ of rivets?
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A. Tearing

B. Shearing

C. None of these

D. Tearing of the plate across a row

3585. In packed absorption tower, onset of flooding usually occurs at a pressure drop of about ______________ mm of water column per metre height of packing?
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A. 25-50

B. 750-1000

C. 50-75

D. 200-250

3586. A pressure vessel is said to be made of thick shell, if the ratio of its diameter to wall thickness is_______________?
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A. > 20

B. < 10

C. < 20

D. > 10
3587. The most common standard size of bubble caps used in industrial operation is___________________?
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A. 1? dia cap with 0.5? dia riser

B. 8? dia cap with 1? dia riser

C. 4? dia cap with 8? dia riser

D. 6? dia cap with 4? dia riser
3588. Vapor velocity in a distillation column for non-foaming mixture is in the range of ______________ times the flooding velocity?
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A. 1.5 to 2

B. 0.6 to 0.7

C. 0.85 to 0.95

D. 0.1 to 0.3

3589. The retention time of material in a rotary dryer depends upon its ______________________?
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A. All A., B. and C.

B. Flights arrangement

C. Slope & length

D. rpm

3590. In a distillation column, minimum clearance to be maintained between the overflow weir and the last row of the bubble caps is ______________ cms?
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A. 20

B. 15

C. 7.5

D. 2.5

3591. The units of Youngs modulus of elasticity and ________________ are the same?
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A. Strain

B. None of these

C. Stress

D. Modular ratio

3592. Baffles are provided in a shell and tube heat exchanger to increase the turbulence and velocity of the shell side fluid. Which of the following shaped baffles does not fall in the category of transverse baffle ?
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A. Disk type baffle

B. Helical type baffle

C. Segmental baffle

D. Flat plate extending across the wall
3593. Overall tray efficiency of a distillation column is the ratio of the number of ___________________?
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A. Ideal trays required to the number of real trays required

B. Overall gas transfer units to the number of ideal trays required

C. Real trays required to the number of ideal trays required

D. None of these

3594. The thermal stress in a metallic bar does not depend upon the_____________________?
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A. Changes in temperature

B. Cross-sectional area

C. Both A. and B.

D. Neither A. nor B.

3595. Longitudinal stress induced in a thin walled cylindrical storage vessel is __________________?
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A. pD/3t

B. pD/6t

C. pD/4t

D. pD/2t

3596. In packed towers provided with saddle packing, liquid redistributors are positioned at every _______________ times column diameter or 6 metres whichever is less?
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A. 5-8

B. 20-25

C. 3-Feb

D. 15-Oct

3597. The optimum size ratio for two mixed reactors in series depends on the kinetics of the reaction and the conversion level. For reaction orders more than one, the_________________?
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A. None of these

B. Smaller reactor should come first

C. Larger reactor should come first

D. Equal sized reactors are the best

3598. The operating pressure drop range in a bag filter is about ______________ mm water gauge?
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A. 1500-2500

B. 50-150

C. 500-1500

D. 10-May

3599. The necessary wall thickness for a metallic storage vessel is a function of the ___________________?
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A. Ultimate tensile strength (or yield point) of the material and operating temperature

B. Diameter of the vessel

C. Operating pressure and welding/joint efficiency

D. All A., B. and C.
3600. For a cylindrical internally pressurised vessel, which of the following closure types would withstand highest pressure, if each closure is of the same material and thickness ?
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A. Ellipsoidal (2 : 1)

B. Hemispherical

C. Flat plate

D. Conical