#### Fluid Mechanics MCQs Competitive – Chemical Engineering MCQs

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#### Latest Chemical Engineering MCQs

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**Latest** Fluid Mechanics Mcqs

The most occurred **mcqs of Fluid Mechanics **in past papers. **Past papers of Fluid Mechanics **Mcqs. **Past papers of** **Fluid Mechanics **Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related **Fluid Mechanics** Mcqs. The Important series of **Fluid Mechanics** Mcqs are given below:

**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 × 103 VOM + 10.94 × 106 V2 OM (SI units) If water is to be used as the fluidising medium, the minimum fluidisation velocity, VOM is_________________?**

A. 24 mm/s **B. 16 mm/s**

C. 12 mm/s

D. 28 mm/s

**For very low pressure and high discharge rate, the compressor used is a/an ______________ compressor?**

A. Reciprocating

B. Axial **C. Rotary**

D. None of these

**The pressure head on sudden contraction in a horizontal pipe is converted into the _____________ head?**

A. Elevation**B. Velocity**

C. Both of the above

D. Neither of the above

**Rise of liquid in a capillary tube is due to_________________?**

A. Adhesion

B. Cohesion **C. Both A. & B.**

D. Neither A. nor B.

**The excess of the sum of pressure & velocity heads over the vapor pressure of the liquid at the suction is called the___________________?**

A. Cavitation sensitivity **B. Net positive suction head (NPSH)**

C. Static submergence

D. Priming

**Co-efficient of discharge (Cd) is defined as actual discharge/theoretical discharge and is equal to Cc . Cv; where Cc = Co-efficient of contraction and Cv = co-efficient of velocity. Cd of an orifice is usually about__________________?**

A. 0.82 **B. 0.62**

C. 0.42

D. 0.98

**The head loss in turbulent flow in a pipe varies________________?**

A. Inversely as the velocity **B. As (velocity)2**

C. Inversely as the square of diameter

D. As velocity

**The fluid property, due to which, mercury does not wet the glass is__________________?**

**A. Surface tension**

B. Cohesion

C. Viscosity

D. Adhesion

**The ratio of inertial forces to elastic forces is called the __________ number?**

A. Reynolds**B. Mach**

C. Weber

D. Euler

**Centrifugal compressors compared to reciprocating compressors__________________?**

A. Have lower operating costs

B. Have quieter operation

C. Require less space **D. All A., B. and C.**

**A fluid element has a velocity V = -y2. xi + 2yx2 . j. The motion at (x, y) = (1/√2, 1) is_________________?**

A. Irrotational and compressible **B. Rotational and compressible**

C. Rotational and incompressible

D. Irrotational and incompressible

**A stream tube is that, which has ______________________ cross-section entirely bounded by stream lines?**

A. A small **B. Any convenient**

C. A circular

D. A large

**Applying a pressure drop across a capillary results in a volumetric flow rate ‘Q’ under laminar flow conditions. The flow rate for the same pressure drop, in a capillary of the same length but half the radius is____________________?**

A. Q/2

B. Q/8

C. Q/4 **D. Q/16**

**The head developed by a centrifugal pump is largely determined by the____________________?**

A. Nature of the liquid being pumped

B. Power of the pump **C. Angle of the vanes and the speed of the tip of the impeller**

D. Vapour pressure of the liquid

**Priming is needed in a ______________ pump?**

A. Gear

B. Reciprocating **C. Centrifugal**

D. Diaphragm

**The Mach number for hypersonic flow of compressible fluid is____________________?**

A. > 1

B. 1 **C. > 4**

D. < 2

**Higher specific speed (200-500) of a centrifugal pump indicates that the pump is of ______________ flow type?**

**A. Axial**

B. Mixed

C. Radial

D. None of these

#### Furnace Technology Mcqs

**Which of the following properties of a fluid is responsible for offering resistance to shear ?**

A. Specific gravity **B. Viscosity**

C. Surface tension

D. All A., B., and C.

**Power required for mixing Newtonian fluids is a function of the _________________?**

A. Speed of impeller, diameter of impeller & viscosity

B. Density of fluid, viscosity of fluid & impeller dia only

C. Density & viscosity of fluid only **D. None of these**

**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?**

**A. 17**

B. 84

C. 42

D. 1.8

**In centrifugal pump operation, the cavitation can be eliminated by maintaining suction pressure ______________ the vapor pressure of the liquid at the suction temperature?**

A. Equal to **B. Higher than**

C. Lower than

D. None of these

**A centrifugal pump is called a turbine pump, if it is having a_________________?**

A. Rotating vaned volute **B. Vaned diffusion casing**

C. Turbine type impeller

D. None of these

**The velocity profile exhibited by laminar flow of Newtonian fluids is such that the velocity distribution w.r.t. radius of the circular pipe is a/an ______________ with the apex at the centre line of the pipe?**

A. Semi-circle **B. Parabola**

C. Hyperbola

D. Semi-ellipse

**The hydrodynamic and thermal boundary layers will merge, when ____________________?**

**A. Prandtl number is one**

B. Nusselt number tends to infinity

C. Schmidt number tends to infinity

D. Archimedes number is greater than 10000

**The energy equation, E + (p/ρ) + (V2/2g) + gZ = constant (E = internal energy/mass), is applicable to___________________?**

A. Isothermal flow of gases

B. Perfect gases only

C. Adiabatic unsteady flow of gases**D. All compressible fluids**

**A Rotameter works on the principle of _______________ pressure drop?**

**A. Constant**

B. Variable

C. Both of the above

D. Neither of the above

**The equivalent diameter for flow through a rectangular duct of width B and height H is___________________?**

A. HB/(H + B)

B. HB/2 (H + B) **C. 2HB/(H + B)**

D. 4HB/(H + B)

**Mass velocity in case of steady flow and through a constant cross-section conduit is independent of the _________________?**

A. Pressure

B. Temperature **C. Both A. & B.**

D. Neither A. nor B.

**Where does the maximum stress occur in case of laminar flow of incompressible fluid in a closed conduit of diameter ‘d’ ?**

A. At d/4 from the wall

B. At the centre **C. At the wall**

D. At d/8 from the wall

**Upto what value of ‘Mach number’, a fluid may be considered as incompressible ?**

A. 3 **B. 0.3**

C. 0.03

D. 10

**Velocity distribution for flow between two fixed parallel plates_________________?**

**A. Varies parabolically across the section**

B. Is zero at the plates and increases linearly to the mid-plane

C. Is constant over the entire cross-section

D. None of these

**The variable required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost is P. Inlet pressure Q. Compressor rpm R. Delivery pressure S. Volumetric flow rate at inlet ?**

**A. P, Q and R**

B. R and S

C. P and R

D. P, Rand S

**Differential manometer measures the____________________?**

A. Sub-atmospheric pressure

B. Atmospheric pressure **C. Pressure difference between two points**

D. None of these

**Medium viscosity lubricating oil can be most ideally pumped by a ______________ pump?**

**A. Vane**

B. Centrifugal

C. Piston

D. Plunger

**With increase in temperature, the vapor pressure of liquids__________________?**

**A. Increases**

B. Decreases

C. Increases linearly

D. Remain constant

**Remote control valve is a _______________ valve?**

A. Needle **B. Butterfly**

C. Gate

D. Globe

**Most of the centrifugal pumps used in chemical plants are usually ____________________ driven?**

A. Diesel engine

B. Steam **C. Electric motor**

D. Gas turbine

**The uniformity of a gas fluidised bed depends upon the _______________ of the solid particles?**

A. Surface properties

B. Size **C. Both A. and B.**

D. Neither A. nor B.

**Permanent loss in a Venturimeter is about ___________ percent of the pressure drop in the upstream cone?**

A. 40 **B. 10**

C. 1

D. 70

#### Chemical Engineering Basics Mcqs

**Mass velocity is independent of temperature & pressure, when the flow is______________________?**

A. Steady through changing cross-section

B. Unsteady through unchanged cross-section **C. Steady and the cross-section is unchanged**

D. Unsteady and the cross-section is changed

**Water hammer in a pipeline results from the____________________?**

A. Pressure increase due to closure of a valve resulting in decrease in rate of flow **B. Rapid pressure change due to a rapid change in the rate of flow**

C. Bursting of pipelines due to closure by a valve

D. None of these

**Kinetic energy of fluid per unit weight represented by the velocity head is given by___________________?**

A. ρv2/gc **B. v2/2gc**

C. 2v2/gc

D. ρ.v2/2gc

**If the discharge of a centrifugal pump is throttled, then its suction lift_______________________?**

**A. Increases**

B. Remains unchanged

C. Decreases

D. Data insufficient to predict

**With increase in the shear rate, the apparent viscosity of pseudo-plastic fluids__________________?**

A. Remain same **B. Decreases**

C. Increases

D. May increase or decrease; depends on the magnitude of shear rate

**A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke’s law. A particle B with diameter 20 microns settling in the same oil will have a settling velocity ?**

A. Twice as that of A **B. One fourth as that of A**

C. Same as that of A

D. Four times as that of A

**A piezometer opening measures the _____________ fluid pressure?**

A. Total **B. Undisturbed**

C. Static

D. Dynamic

**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) ?**

A. 24

B. 24000

C. 0.24**D. 0.44**

**For the same terminal conditions and valve size, the pressure drop in a fully opened globe valve as compared to that in a gate valve is___________________?**

**A. More**

B. Equal

C. Less

D. Either A. or B depends on the viscosity of the fluid

**Maximum theoretical suction lift for water at 15°C by a centrifugal pump is 34 ft. The same for water at 90°C will be _____________________ ft?**

A. 34

B. 40 **C. 8**

D. 37

**The terminal velocity of a particle moving through a fluid varies as dp n. The value of n is equal to _______________ in Stoke’s law regime?**

A. 0.5

B. 1 **C. 2**

D. 1.5

**Which is the correct relationship for a centrifugal pump? (Where, D = Impeller diameter, inches H = Head developed, ft of liquid pumped N = Speed of pump, rpm) ?**

**A. D = 1840 H0.5/N**

B. H = 1840 D0.5/N

C. D = 1840 N/H0.5

D. D = 1840 H/N

**Pump used for the transportation of molten sodium in a fast breader reactor is a/an __________ pump?**

A. Plunger

B. Reciprocating **C. Electromagnetic**

D. Gear

**Head developed by a centrifugal pump depends on its___________________?**

A. Impeller diameter

B. Speed **C. Both A. and B.**

D. Neither A. nor B.

**Check valve provided in the discharge line of a centrifugal pump serves the purpose of controlling the_______________?**

**A. Back flow of fluid in the event of stoppage of pump**

B. Flow of liquid during operation of the pump

C. Discharge pressure

D. All A., B. and C.

**At high Reynolds number_________________?**

**A. Inertial forces control and viscous forces are unimportant**

B. Inertial forces are unimportant and viscous forces control

C. Viscous forces predominate

D. None of these

**Sewage sludge is ______________ type of non-Newtonian fluid?**

A. Pseudo plastic **B. Bingham plastic**

C. Dilatant

D. None of these

**Cavitation can be prevented by________________?**

A. Maintaining suction head = developed head **B. Maintaining the suction head sufficiently greater than the vapour pressure**

C. Suitably designing the pump

D. Maintaining suction head lower than the vapour pressure

**In fluid flow, cavitation is caused, if the____________________**

A. Total energy decreases

B. Fluid velocity decreases to zero

C. Both A. and B.**D. Flow pressure approaches its vapor pressure at the prevailing temperature**

**For the transfer of solution of thick slurry, the pump used is a _____________ pump?**

A. Gear

B. Reciprocating **C. Diaphragm**

D. Centrifugal

**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________________?**

A. 45 **B. 60**

C. 90

D. 30

**Shear stress in a fluid flowing in a round pipe_________________?**

A. Remains constant over the cross-section

B. Varies parabolically across the cross-section **C. Is zero at the centre and varies linearly with the radius**

D. Is zero at the wall and increases linearly to the centre

**Capillary rise of mercury in a small diameter tube is proportional to (where, d = diameter of the tube, ζ = surface tension of mercury)____________________?**

A. 1/d

B. d **C. ζ**

D. 1/ζ

**Hydraulic mean depth (Dm) for a circular pipe of diameter ‘D’ flowing full is 0.25 D. For a circular channel, at Dm = 0.3 D, gives the condition for the maximum ?**

A. Flow rate**B. Mean velocity**

C. Both a & b

D. Neither a nor b

#### Fluid Mechanics Mcqs

**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________________?**

**A. 4.4 KPa**

B. 3.7 KPa

C. 2.94 KPa

D. None of these

**Which of the following denotes the effect of compressibility in fluid flow ?**

A. Euler number **B. Mach number**

C. Weber number

D. Reynolds number

**Reynolds number for water flow through a tube of I.D. 5 cm is 1500. If a liquid of 5 centipoise viscosity and 0.8 specific gravity flows in the same pipe at the same velocity, then the pressure drop will______________________?**

**A. Increase**

B. Remain same

C. Decrease

D. Data insufficient to predict pressure drop

**The ratio of the depth of flow to the hydraulic radius for the most economical trapezoidal section, in open channel flow is_____________________?**

A. 1

B. 0.5

C. 1.5**D. 2**

**Which of the following equations as suggested by Colebrook and White gives the increase in roughness of a new surface (ε0) with age/time (t) (where, ε = roughness of the surface after time’t’. α = a co-efficient to be experimentally determined) ?**

**A. ε = ε0 + α.t**

B. ε = ε0 + α.t3

C. ε = ε0 + α.t2

D. ε = ε0 + α.t4

**______________ pumps are axial flow pumps?**

A. Diffuser **B. Propeller**

C. Turbine

D. None of these

**In a fully turbulent flow (Re > 105) in a pipe of diameter ‘d’, for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is_______________?**

A. d2

B. d **C. d2.5**

D. d4

**For a particle settling in water at its terminal settling velocity, which of the following is true ?**

A. Drag = buoyancy + weight **B. Weight = buoyancy + drag**

C. Buoyancy = weight + drag

D. Drag = weight

**Gear pump_________________?**

**A. Is a positive displacement pump**

B. Is a non-positive displacement pump

C. Is a centrifugal pump

D. Can be started with delivery valve closed

**Most commonly used joint in the underground pipe lines is the________________?**

**A. Sleeve joint**

B. Flange

C. Coupling

D. Expansion joint

**Ratio of pressure and inertia force gives ______________ number?**

A. Mach

B. Weber **C. Euler**

D. Froude

**With increasing flow rate, the hydraulic efficiency of a centrifugal pump__________________?**

**A. Monotonically decreases**

B. Remains constant

C. Decreases and then increases

D. Increases and then decreases

**Steady uniform flow is represented by flow through a/an ___________________?**

**A. Long pipe at constant rate**

B. Expanding tube at constant rate

C. Long pipe at decreasing rate

D. None of these

**Which of the following is not a dimension-less parameter ?**

A. Specific gravity

B. Euler number

C. Fanning friction factor**D. None of these**

**A fluid is the one, which___________________?**

**A. Cannot remain at rest under the action of shear force**

B. Is incompressible

C. Continuously expands till it fills any container

D. Permanently resists distortion

**Brownian movement is prominent in the particle size range of _____________ microns in case of settling of a particle in a fluid?**

**A. 2 to 3**

B. 200 to 300

C. 0.01 to 0.10

D. 100 to 1000

**The velocity profile for turbulent flow through a closed conduit is_______________?**

**A. Logarithmic**

B. Hyperbolic

C. Parabolic

D. Linear

**Nominal size of a pipe is an indication of its ______________ diameter?**

A. Outer

B. Inner **C. Approximate**

D. None of these

**The fluid in which the shearing stress within it is proportional to the velocity gradient across the sheared section, is called a _____________ fluid?**

A. Perfect **B. Newtonian**

C. Bingham

D. None of these

**With increase in pump speed, its NPSH requirement_________________?**

A. Remains unaltered **B. Increases**

C. Decreases

D. Can either increase or decrease; depends on other factors

**Pressure drag does not depend upon the_________________?**

A. Pressure of main flow only

B. Roughness of surface of the body

C. Length of the body in flow direction**D. All A., B. and C.**

**The exit cone angle in case of a standard Venturimeter is _____________ the entrance cone angle?**

**A. Smaller than**

B. Equal to

C. Greater than

D. Either A. or B.

**Molten soap mass is transported by a ______________ pump?**

A. Reciprocating

B. Diaphragm

C. Gear**D. Centrifugal**

**Assuming flow to be laminar, if the diameter of the pipe is halved, then the pressure drop will_______________?**

**A. Increase**

B. Remain same

C. Decrease

D. Be quadrupled

**Dimension of surface tension is (where, F = force, L = length) ?**

**A. FL-1**

B. F.L-2

C. F-1. L

D. F-2. L

**The schedule number of a pipe is an indication of its_________________?**

A. Roughness

B. Size

C. Material density**D. Wall thickness**

**A fluid is a substance, that_________________?**

A. Has to be kept in a closed container

B. Has zero shear stress

C. Is almost incompressible **D. Flows when even a small shear is applied to it**

**The continuity equation__________________?**

**A. Relates mass flow rate along a stream tube**

B. Stipulates that Newton’s second law of motion must be satisfied at every point in the fluid

C. Relates work and energy

D. None of these

**The flow of gas along a pipe in the direction of decreasing pressure causes decrease in its__________________?**

A. Velocity **B. Specific volume**

C. Viscosity

D. None of these

**In case of supersonic flow of a fluid through pipeline, the ‘Mach number’ is__________________?**

A. 1

B. 0

C. < 1**D. > 1**

**Gradually varied flow in open channel is a/an ____________ flow?**

A. Unsteady uniform **B. Steady non-uniform**

C. Steady uniform

D. Unsteady non-uniform

**Stoke’s law is valid, when NRe, p is less than_________________?**

**A. 2**

B. 2100

C. 100

D. 700

**Cavitation in a centrifugal pump can be avoided by keeping the__________________?**

**A. Inlet pressure high**

B. Inlet pressure low

C. Outlet pressure low

D. Outlet pressure high

**Momentum transfer in laminar flow of fluids results due to the_________________?**

A. Density

B. Viscosity **C. Velocity gradient**

D. None of these

**What is the ratio of fluid carrying capacity of two pipes having diameters d1 and d2 respectively ?**

A. d1/d2 **B. (d1/d2)0.5**

C. (d1/d2)0.8

D. (d1/d2)2

**Mach number is important in a fluid flow problem, when the inertia and _____________ forces predominate?**

**A. Elastic**

B. Gravity

C. Viscous

D. None of these

**Boundary layer thickness in turbulent flow over a flat plate increases as(where, d = distance from the leading edge.) ?**

A. d2/3

B. √d **C. d4/5**

D. d1/3