chemical engineering MCQs – Page 193

Practise multiple-choice questions from chemical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering Mcqs

3841. Multiple blade paddle agitator is used for mixing high viscosity liquids/paste in which the paddle diameter is commonly 0.8 times the tank diameter. However, the width of the blade is in the range of ______________ times the paddle diameter?
0

A. 0.65 to 0.80

B. 0.3 to 0.5

C. 0.1 to 0.25

D. 0.5 to 0.6

3842. In the design of a paddle agitator, the ratio (paddle dia/tank dia) is normally taken as___________________?
0

A. 0.5

B. 0.8

C. 0.25

D. 0.1

3843. The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is__________________?
0

A. Dependent on NRe only

B. 4.36

C. 120.36

D. 2.36

3844. The safe height (h) to diameter D. ratio (i.e., h/d) for liquid/petro fuel storage tank of capacity more than 45 kilolitres is less than _________________?
0

A. 3.5

B. 3

C. 1

D. 2

3845. What is the slope of the operating line in the rectifying section of a distillation column ?
0

A. 0

B. ?

D. > 1

3846. _____________ heat exchanger is also known as hair pin type exchanger?
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A. Finned

B. Plate type

C. Double pipe

D. Regenerative

3847. Weep holes provided in the plates of a distillation column ____________________?
0

A. Must be large enough (usually 1/4? to 5/8? dia) to prevent plugging but should not deliver

B. lows approximately the same path as the overflow fluid

C. All A., B. and C.

D. Facilitate draining out liquid from a tray when the unit is not in operation

E. essive amount of fluid during operation

F. Are normally located near the overflow weir so that any delivery of liquid during operation

3848. In a shell and tube heat exchanger, floating head is used for _________________?
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A. High heat transfer co-efficient

B. Large temperature differentials

C. Low pressure drop

D. Less corrosion of tubes

3849. The overall resistance for heat transfer through a series of flat resistance, is the _____________ of the resistances?
0

A. Sum

B. Average

C. Product

D. Geometric mean

3850. The advantage of using a 1 2 shell and tube heat exchanger over a 1 1 shell and tube heat exchanger is_________________?
0

A. Higher tube side heat transfer co-efficient

B. Lower shell side pressure drop

C. Higher shell side heat transfer co-efficient

D. Lower tube side pressure drop

3851. At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ?
0

A. 0.5

B. < 0.5

C. < 0.1

D. > 0.6

3852. Larger depth of liquid on the trays of a distillation column_________________?
0

A. Leads to high tray efficiency

B. Results in higher pressure drop per tray

C. Both A. & B.

D. Neither A. or B.

3853. Optimum economic pipe diameter for fluid flow is determined by the____________________?
0

A. Density of the fluid

B. Viscosity of the fluid

C. Total cost considerations (pumping cost plus fixed cost of the pipe)

D. None of these

3854. Thermal diffusivity of a material __________________?
0

A. Is defined as K/? . Cp

B. Is the ratio of thermal conductivity to thermal capacity

C. Has the unit m2 /sec

D. All A., B. and C.

3855. If a single tube pass heat exchanger is converted to two passes; for the same flow rate, the pressure drop per unit length in tube side will _____________ times?
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A. Increase by 1.8

B. Decrease by 22

C. None of these

D. Increase by 21.6

3856. Any shell opening greater than 5 cms for a storage tank must be reinforced for reason of ____________________?
0

A. None of these

B. Preventing the local overstressing of the shell around the opening

C. Making the joint leak proof

D. Reduction of discontinuity in shape at the junction

3857. The ratio, (propeller agitator dia/tank dia) is normally taken as____________________?
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A. 0.15-030

B. 0.60-0.90

C. 0.75-0.85

D. 0.5-0.65

3858. In case of heat transfer by conduction in a hollow cylinder, ______________ mean area is used to calculate the heat transfer rate?
0

A. Either A., B. or C.

B. Geometric

C. Arithmetic

D. Logarithmic

3859. Typical static submergence for bubble cap plate column operating at atmospheric pressure may be around _________________?
0

A. 2.5?

B. 5?

C. 50% of the plate spacing

D. 0.5?

3860. In a cylindrical vessel subjected to internal pressure, the longitudinal stress ?L and the circumferential stress, ?n are related by___________________?
0

A. No relation exists

B. ?h = ?L/2

C. ?h = 2 ?L

D. ?h = ?L

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