chemical engineering Mcqs
3951. Tube height in a calandria type evaporator is normally less than _______________ metres?
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A. 3.5

B. 2

C. 5.5

D. 1

3952. Boiling point of a solution according to Duhrings rule is a linear function of the _____________ of water?
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A. Density

B. Thermal conductivity

C. Boiling point (at the same pressure)

D. Viscosity

3953. Radiation energy is emitted by all the substances, which are above____________________?
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A. 0K

B. 100C

C. Room temperature

D. 0C

3954. A forced circulation long tube vertical evaporator as compared to the natural circulation evaporator__________________?
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A. Is economical in operation

B. Employs high velocity, high heat transfer rate and less heating surface requirement

C. Employs a centrifugal pump placed between external downtake from vapor drum and inlet to

D. e bundle

E. Both B. & C.
3955. Evaporator tubes are generally_____________________?
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A. Inclined

B. Random

C. Horizontal

D. Vertical
3956. Fouling factor for a heat exchanger is given by (where, U1 = heat transfer co-efficient of dirty surface U2 = heat transfer co-efficient of clean surface) ?
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A. 1/U1 1/U2

B. 1/U2 1/U1

C. U1 U2

D. U2 U1

3957. The thermal boundary layer at NPr > 1 ?
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A. Is thinner than hydrodynamic boundary layer

B. Is thicker than hydrodynamic boundary layer

C. Disappears

D. And the hydrodynamic boundary layers are identical

3958. Peclet number (Pe) is given by____________________?
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A. Pe = Re.Pr

B. Pe = Nu.Re

C. Pe = Re/Pr

D. Pe = Pr/Re

3959. An ejector is used to__________________?
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A. Remove condensate

B. Increase pressure

C. Increase temperature

D. None of these
3960. In a forward feed multiple effect evaporator unit__________________?
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A. No pump is required to withdraw the product from the last effect

B. Viscosity of liquid is highest in first effect

C. Transfer from effect to effect is done by pumps

D. None of these
3961. A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when_________________?
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A. CPA > CPB

B. CPA < CPB

C. kA < 0.5 kB

D. kA >2 kB

3962. Slope of counter-current flow rotary drier is in the range of ____________ meter/metre?
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A. 0 to 2.2

B. 0 to 0.08

C. 0 to 0.8

D. 0 to 1.5

3963. An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a_________________?
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A. Heat exchanger

B. Boiler

C. Recuperator

D. Regenerator

3964. Overall heat transfer co-efficient of a particular tube is U1. If the same tube with some dirt deposited on either side has coefficient U2, then_________________?
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A. U2 > U1

B. U1 = dirt factor U2

C. U1 > U2

D. U1 = U2
3965. The Graetz number is concerned with the___________________
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A. Mass transfer between a gas and a liquid

B. Absorption with chemical reaction

C. Heat transfer in laminar flow

D. Heat transfer in turbulent flow

3966. Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer cannot take place____________________?
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A. Between two bodies in physical contact with each other

B. Between two bodies not in physical contact with each other

C. From one part of a body to the another part of the same body

D. Both B & C

3967. Hole diameter of the sieve trays in the distillation column ranges from ______________ mm?
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A. 4 to 8

B. 3 to 12.5

C. 1 to3

D. 12.5 to 18.5

3968. Floating head heat exchangers are used for the____________________?
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A. Heat transfer between corrosive fluids

B. Co-current heat transfer systems

C. Counter-current heat transfer systems

D. Cases where temperature difference between the shell and the tubes is more (>50C)
3969. A certain pressure vessel manufacturer avoids doing reinforcements calculations for openings by always providing a reinforcing pad extending upto double the diameter of the opening and of the same material and thickness as that of the shell wall. If area compensation is accepted as a code guideline, his approach leads to safe design____________________?
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A. Only if the opening is on a horizontal cylindrical vessel

B. Irrespective of the shape of the vessel

C. Only if the opening is on spherical vessel

D. Only if the opening is on a vertical cylindrical vessel

3970. Which of the following types of reactors is the safest from operation point of view ?
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A. A vapor phase reactor

B. Pot type reactor

C. A liquid phase catalytic reactor

D. A liquid phase reactor

3971. In Fouriers law, the proportionality constant is called the______________________?
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A. Thermal diffusivity

B. Thermal conductivity

C. Heat transfer co-efficient

D. Stefan-Boltzmann constant

3972. For _______________ Prandtl number values, the heat conduction will be negligible in the buffer zone?
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A. Extremely low

B. No

C. High

D. Low

3973. Rivets are generally specified by the____________________?
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A. Head diameter

B. None of these

C. Overall length

D. Shank diameter
3974. Plancks distribution law is valid for _____________ bodies?
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A. Coloured

B. All A., B. & C.

C. Black

D. White

3975. Duhrings plot is of use in_________________?
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A. Absorption

B. Extractive distillation

C. Leaching

D. Evaporation
3976. A graph between _____________ is called Wilson plot?
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A. (1/U) Vs. (1/v0.8)

B. (1/v0.8) Vs. U

C. v0.8 Vs . U

D. (1/U) Vs. (1/V)

3977. jH factor for heat transfer depends upon the ____________ number?
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A. Prandtl

B. Nusselt

C. Biot

D. Reynolds
3978. Hoop (circumferential) stress induced in a thin walled Horton Sphere used for the storage of liquid ammonia under pressure is____________________?
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A. pD/2T

B. pD/6T

C. pD/4T

D. pD/3T

3979. The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is___________________?
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A. Some

B. Either more or less; depends on the nature of vapor

C. Less

D. More

3980. Critical value of the _____________ number governs the transition from laminar to turbulent flow in free convection heat transfer?
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A. Grashoff

B. Reynolds

C. Both a & b

D. Prandtl & Grashoff
3981. Which of the following efficiencies can be greater than 100% ?
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A. Murphree plate efficiency

B. Overall plate efficiency

C. None of these

D. Point efficiency

3982. The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium. This is ______________ law?
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A. Plancks

B. Kirchoffs

C. Stefan-Boltzmann

D. Wiens displacement

3983. _____________ heat exchanger is used for chilling oil to be dewaxed?
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A. U-tube

B. Floating head

C. Fixed tube

D. Double pipe
3984. A minimum clearance of about _______________ mm is maintained between the distillation column wall and the bubble cap?
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A. 67

B. 38

C. 95

D. 19

3985. Bubble cap plate column is___________________?
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A. A differential stage contactor

B. A finite stage contactor

C. A continuous contactor

D. Used only for distillation, not for absorption

3986. Maximum acceptable total liquid gradient over a tray is about _______________ mm?
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A. 45.5

B. 30.5

C. 5.5

D. 12.5
3987. For what value of Prandtl number, St = f/2 ?
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A. > 1

B. < 1

C. 1

D. 1.5

3988. Seamless pipe is made________________?
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A. From rolled strips formed into cylinders and seam-welded

B. By extrusion & casting into static and centrifugal molds

C. By forging a solid round, piercing it by simultaneously rotating & forcing it over a piercer

D. nt and further reducing it by rolling gas drawing

E. Both B. and C.
3989. Reason for operating an evaporator in multiple effects is to secure ___________________?
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A. Increased steam economy

B. Decreased steam consumption

C. Both A. and B.

D. Increased capacity

3990. Diameter of the sieve tray column is determined by the_________________?
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A. Height of the plate spacing

B. Upper limit of the vapour velocity

C. Lower limit of vapour velocity

D. Hole diameter of the sieve tray

3991. The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are_______________?
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A. Nu, Pr

B. Re.Gz

C. Nu, Gz

D. Nu, Pr, Re

3992. Multiple effect evaporation accounts for___________________?
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A. Lower operating costs

B. Steam economy

C. None of these

D. Investment economy

3993. One kilogram of water at 0C is changed to superheated steam of one atm pressure and 300 C. The major heat consumption in the process will be to________________?
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A. Evaporate the water

B. Heat the water from 0C to 100C

C. Data insufficient, cant be predicted

D. To superheat the steam

3994. When warm and cold liquids are mixed, the heat transfer is mainly by_______________?
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A. Conduction

B. Convection

C. Radiation

D. Both A. & C.

3995. In a co-current double pipe heat exchanger used for condensing saturated steam over the inner tube, if the entrance and exit conditions of the coolant are interchanged, then the rate of condensation will___________________?
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A. Decrease

B. Remain unchanged

C. Either increase or decrease; depends on the coolant flow rate

D. Increase

3996. For heat flow through very thick walled cylinder, use ___________mean radius?
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A. Either A. or C.

B. Geometric

C. Logarithmic

D. Arithmetic

3997. Steam trap is used to_________________?
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A. Remove water resulting from partial condensation of steam

B. None of these

C. Stop the supply of steam

D. Condense the steam flowing in the pipeline

3998. For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is_________________?
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A. (d1 + d2)/d2

B. d2/(d1 + d2)

C. (d1 + d2)/d1

D. d1/(d1 + d2)
3999. In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement ?
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A. efficient

B. e fluid

C. Results in higher shell side pressure drop

D. Creates relatively lower turbulence on the shell side resulting in lower shell side heat transfer

E. Can accomodate less number of tubes for a given shell diameter

F. Facilitates easier shell side cleaning; hence is more suitable for handling high dirt factor shell

4000. Which of the following has maximum thermal conductivity ?
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A. Nitrogen

B. Tar

C. Coal

D. Iron