chemical engineering Mcqs
3651. Baffle width is normally taken as ______________ times the tank diameter?
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A. 0.2-0.45

B. 0.4-0.5

C. 0.45-0.6

D. 0.1-0.12
3652. In a shell and tube heat exchanger, the shortest centre to centre distance between the adjacent tubes is__________________?
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A. Always less than the diameter of the tube

B. Called tube clearance

C. None of these

D. Called tube pitch
3653. The type of stress developed in a metallic bar on subjecting it to a change in temperature without allowing it to be deformed is ______________ stress?
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A. Thermal

B. Tensile

C. Compressive

D. Shear

3654. The equivalent diameter for pressure drop is _______________ that for heat transfer?
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A. Equal to

B. Smaller than

C. Greater than

D. Not related with
3655. Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than ______________ kilolitres?
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A. 45

B. 30

C. 20

D. 85

3656. In a pressure vessel containing multiple openings of various dimensions at different parts, stress concentration at the edges of the opening is maximum which becomes negligibly small beyond the area covered by ______________ times the hole diameter?
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A. Ten

B. Twenty

C. Five

D. Two
3657. Wall thickness of schedule 40 pipe as compared to that of schedule 80 pipe is ___________________?
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A. More

B. Less

C. Same

D. Either A. or B.; depends upon the I.D. of the pipe

3658. For turbulent flow (NRe > 2100) of low viscosity fluid (? > 20cp) in steel pipes, the optimum inside pipe diameter is given by(where, Q = fluid flow rate, ft3/sec, ? = fluid density, lb/ft3 ? = fluid viscosity, centipoise Di = optimum inside pipe diameter, inches) ?
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A. Di, opt = 3.9 Q0.45. ?0.95

B. Di, opt = 3 Q0.36. ?0.88

C. Di, opt = 3.9 Q0.45 ?0.13

D. Di, opt = 4.7 Q0.36. ?3.2?0.13

3659. Scale up problem in design based on the similarity concept takes into account _______________ similarity?
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A. Geometrical

B. Kinematic

C. Dynamic

D. All A., B. and C.
3660. Elastic failure of a material occurs, when the tensile stress equals yield strength, yield point or the elastic limit. Also, the elastic failure occurs according to maximum strain theory, when the maximum tensile strain equals (where, ? = yield strength and E = modulus of elasticity) ?
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A. E/?

B. E

C. ?

D. ?/E
3661. Smaller sized packings are generally dumped to the packed columns, and the large ones of size greater than ______________ mm are stacked individually, which provides better control over bed porosity and offers lower gas pressure drop?
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A. 50

B. 150

C. 25

D. 75
3662. Minimum baffle spacing recommended in a shell and tube heat exchanger is equal to _____________________?
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A. 40% of the I.D. of the shell

B. 25 cms

C. 5 cms

D. I.D. of the shell

3663. For identical situation, condensing film coefficient in case of a horizontal condenser is almost ______________ the value expected in case of vertical condenser?
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A. Twice

B. Five times

C. Half

D. Thrice
3664. Steam economy is defined as the amount of evaporation per unit amount of steam used, while the capacity is the total evaporation obtained per hour. Use of multiple effects in evaporation ?
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A. Increases capacity

B. Increases economy

C. Does not affect the capacity

D. Both B. & C.
3665. Baffles may be eliminated for_________________?
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A. Low viscosity liquids (< 200 poise)

B. Large diameter tanks

C. High viscosity liquids (> 600 poise)

D. None of these

3666. The operating velocity in the absorption tower is usually 40-50% of the flooding velocity. Packed absorption towers are normally designed for a pressure drop of about _________________ mm of water column per metre height of packing?
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A. 20-40

B. 5-Jan

C. 1000-1500

D. 100-150

3667. Which of the following packing materials provides for maximum mass transfer ?
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A. Raschig rings

B. All give the same value

C. Raschig rings

D. Cross-partition rings
3668. Overall mass transfer co-efficient in case of absorption of __________ in water is based on the gas film co-efficient only, as the mass transfer process is gas film (phase) controlling ?
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A. None of these

B. SO2

C. CO2

D. NH3
3669. For high pressure process equipments/vessels, the connected nozzle should be____________________?
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A. Screwed

B. Flanged

C. Brazed

D. Welded

3670. With increase in pressure drop (for a given particle size), the dust collection efficiency of a cyclone separator will________________?
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A. Remain unaffected

B. Increase or decrease depending on the nature of the dust

C. Increase

D. Decrease

3671. The absorption factor is defined as (where, S1 = slope of the equilibrium curve, S2 = slope of the operating line) ?
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A. S1.S2

B. 1/S1.S2

C. S2/S1

D. S1/S2
3672. The slope of the feed line in distillation operation is given by (where, q = fraction of the feed stream that is liquid ?
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A. None of these

B. #NAME?

C. -q/(1-q)

D. #NAME?

3673. 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 ?
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A. Flat plate

B. Ellipsoidal

C. Hemispherical

D. Torispherical

3674. A claming section before the liquid flows into the downcomer is provided to__________________?
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A. Cool the liquid before it flows down

B. Reduce the discharge fluctuation

C. Ensure better vapour-liquid contact

D. Permit release of entrained vapour in the liquid
3675. Which of the following factors affect the pressure drop in a co-current gas-liquid absorption packed tower ?
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A. All A., B. and C.

B. Size, shape, orientation and surface of the packing particles

C. Density and viscosity of fluids

D. Fluid flow rates

3676. Pick out the correct statement___________________?
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A. None of these

B. Centre to centre distance between two consecutives rivets in a row is called the pitch

C. A riveted joint made in overlapping plates is called butt joint

D. Hole size drilled in riveted plates is less than the actual size of the rivet

3677. The thickness of segmental baffles (25 -35% cut truncated plates usually) is generally _____________ the tube wall thickness?
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A. Twice

B. Half

C. Four times

D. Equal to

3678. The ratio of shear stress to shear strain is called ____________________?
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A. Bulk modulus

B. Modulus of rigidity

C. Shear modulus

D. Modulus of elasticity

3679. The equivalent diameter for fluid flow through a channel of constant non-circular cross section of area A is given by (where, P = perimeter of the channel in contact with the fluid) ?
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A. A/P

B. ?A

C. 4 P/A

D. 4 A/P
3680. _____________________ tray arrangement is recommended for distillation column having diameter upto 4 ft ?
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A. Radial flow

B. Split flow

C. Cross flow

D. Cascade

3681. Normally, the length to diameter ratio of rotary dryers varies from 4 to 10 and for its economic operation; the number of transfer units (NTU) for such dryers varies from ?
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A. 3.5-5.5

B. 1.5-2.5

C. 7.5-10.0

D. 15-Oct

3682. Maximum allowable vapour velocity in a bubble cap tower is determined by the ____________________?
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A. None of these

B. Diameter of the column

C. Entrainment considerations

D. Vapour density

3683. The slope of operating line in the rectifying section of a distillation column is unity, if the reflux ratio is___________________?
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A. 0

B. Minimum

C. 1

D. ?
3684. For storing hazardous chemicals in large storage tanks, the minimum safe distance between the two tanks should range between ______________________ times the tank diameter?
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A. 2.5 to 3.5

B. 1 to 1.5

C. 4 to 5

D. 6 to 8

3685. In a distillation column, the minimum residence time for liquid in the downspout is about ______________ seconds?
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A. 80

B. 8

C. 180

D. 1

3686. In the design of a bag filter, the gas temperature is an important consideration, as it affects the___________________?
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A. Gas viscosity

B. Fibre selection

C. All A., B. & C.

D. Gas density

3687. For given number of passes, pitch & tube diameter, the maximum number of tubes that can be accommodated in a shell of tripled inside diameter will be ____________ times?
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A. About 9

B. Considerably less than 9

C. About 3

D. Considerably more than 9
3688. Vertical condenser is advantageous to the horizontal condenser from operation point of view, when________________?
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A. Hydrostatic head is required for refluxing the condensate

B. Only the function of condensation is to be carried out

C. Sub-cooling of condensate is desired

D. Both the functions of condensation & sub cooling are carried out in a single unit
3689. At the following point for a given packing and set of fluids, the pressure drop per metre of packed height, with variation in fluid rates and operating pressure____________________?
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A. Increases

B. Decreases

C. May increase or decrease depending upon the solubility of the gas in the liquid

D. Remain same
3690. Generally, no corrosion allowance in wall thickness of a part is required, if the thickness is more than ______________ mm?
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A. 30

B. 5

C. 10

D. 20

3691. A/an _______________ is used for changing the direction of a pipeline?
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A. Disc compensator

B. Elbow

C. Flange

D. Union

3692. In case of a shell and tube heat exchanger, the effect of L/D on inside film heat transfer coefficient (hi) vanishes after a Reynold number of_____________?
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A. 10000

B. 3000

C. 1000

D. 5000

3693. Which of the following is not a graphical method (but is an analytical method) for the calculation of theoretical number of stages in case of continuous binary distillation ?
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A. McCabe-Thieles method

B. None of these

C. Ponchon-Savarit method

D. Sorel-Lewis method
3694. A pipe is generally made of circular cross-section, because a circular cross-section has the____________________?
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A. Higher structural strength

B. Lowest surface area requirement for a given volume

C. Both A. & B.

D. None of these

3695. Removable connection of tubes to tube sheet is called___________________?
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A. Nipple

B. Ferrule

C. Saddle

D. Socket

3696. In a shell and tube heat exchanger having triangular pitch, the shell side equivalent diameter is given by________________?
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A. (4P2 + ?d2/4)/?d

B. (P2 ?d2/4)/?d

C. 4(0.86P2 ?d2/4)/?d

D. 4(0.86P2 ?d2)/?d

3697. It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than _________________?
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A. 0.55

B. 0.80

C. 0.95

D. 0.99

3698. Triangular pitch tube layout as compared to square pitch in a shell and tube heat exchanger________________?
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A. Permits the use of less tubes in a given shell diameter

B. Facilitates comparatively easier external cleaning because of large clearance

C. Permits the use of more tubes in a given shell diameter

D. Both B. and C.

3699. Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is_______________?
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A. Same

B. About 3 times

C. Less

D. About 0.33 times

3700. Fouling factor must be included in the calculation of overall design heat transfer coefficient, when the liquid__________________?
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A. Is of high specific gravity

B. Containing suspended solids flows at high velocity

C. Is highly viscous

D. Containing suspended solids flows at low velocity