chemical engineering fluid mechanics for chemical chemical engineering Mcqs
201. ______________ is an example of axial flow impeller?
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A. Propeller

B. Turbine

C. Paddle

D. All A., B. and C.

202. Cavitation occurs in a centrifugal pump when the suction pressure is________________?
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A. Greater than the vapour pressure of the liquid at that temperature

B. Equal to the vapour pressure

C. Less than the vapour pressure of the liquid at that temperature

D. Equal to the developed head

203. A 2? gate valve fitted in a pipe is replaced by a similar globe valve. Pressure drop in gate valve was ?p. For the same discharge, the pressure drop across globe valve is__________________?
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A. > ?p

B. < ?p

C. ?p

D. ?p2

204. Pumping of a corrosive liquid is generally preferred to be done by a ______________ pump, as it can be made of a variety of materials including plastics?
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A. Positive displacement

B. Gear

C. Sump

D. Piston

205. The curve of metacentre for a floating body ____________ the curve of buoyancy?
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A. Is always below

B. Is the evolute of

C. Is tangential to

D. Intersects at right angle

206. In case of turbulent flow of a Newtonian fluid in a straight pipe, the maximum velocity is equal to (where, Vavg = average fluid velocity)?
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A. 1.8 Vavg

B. 1.2 Vavg

C. Vavg

D. 1.5 Vavg

207. Ratio of pressure and inertia force gives ______________ number?
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A. Mach

B. Froude

C. Euler

D. Weber

208. An ideal plastic substance indicates no deformation, when stressed upto yield stress, but behaves like a Newtonian fluid beyond yield stress. Which of the following is an ideal plastic ?
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A. Sugar solution

B. Blood

C. Sewage sludge

D. Rubber latex

209. The contraction co-efficient for Bordas mouthpiece (for frictionless fluid) is__________________?
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A. 0.5

B. 0.1

C. 0.94

D. 1

210. The range of a particular Rotameter can be increased by__________________?
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A. Decreasing the diameter of the float

B. No means

C. Use of floats of different densities

D. Increasing the diameter of the float

211. Differential manometer measures the___________________?
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A. Pressure difference

B. Gauge pressure

C. Pressure gradient

D. Absolute pressure

212. For turbulent fluid flow in pipe, the expression for Prandtl one seventh power law is (where, r = pipe radius, x = distance) ?
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A. None of these

B. V/Vmax = (r/x)1/7

C. V/Vmax = (x/r)1/7

D. V/Vmax = (x.r)1/7

213. The value of critical Reynolds number for pipe flow is_________________?
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A. None of these

B. 10,000

C. 1,300

D. 100,000

214. Nominal size of a pipe is an indication of its ______________ diameter?
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A. None of these

B. Outer

C. Inner

D. Approximate
215. For very low pressure and high discharge rate, the compressor used is a/an ______________ compressor?
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A. None of these

B. Reciprocating

C. Axial

D. Rotary
216. The ratio of actual discharge to theoretical discharge through an orifice is equal to______________?
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A. Cv . Cd

B. Cd/Cv

C. Cc . Cd

D. Cc . Cv
217. Curve III in the bellow diagram represents a/an________________?
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A. Dilatent fluid

B. None of these

C. Pseudo plastic fluid

D. Ideal plastic

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

219. Check valve is used for ________________ flow?
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A. None of these

B. Unidirectional

C. Very precise control of

D. Multidirectional

220. The losses in open channel flow generally vary as the ________________?
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A. Inverse of the roughness

B. Inverse square of hydraulic radius

C. Square of the velocity

D. First power of the roughness
221. A centrifugal pump designed to pump water is employed to pump a more viscous oil. In the later case, the pump_________________?
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A. Develops a lower head

B. Requires more power

C. Capacity is reduced

D. All A., B. and C.
222. The discharge through a rectangular weir varies as ___________________?
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A. H2/5

B. H5/2

C. H1/2

D. H3/2
223. Hydraulic diameter for non-circular ducts is equal to ___________ times the area of flow divided by the perimeter?
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A. Eight

B. Four

C. Three

D. Two

224. In case of a centrifugal pump, the theoretical head developed is dependent on the _____________ the impeller?
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A. Speed of

B. All A., B. and C.

C. Diameter of

D. Fluid velocity leaving

225. Two piping system are said to be equivalent, when the ______________ are same?
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A. Length & friction factor

B. Length & diameter

C. Diameter & friction factor

D. Fluid flow rate & friction loss
226. In fluid flow, cavitation is caused, if the____________________?
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A. Fluid velocity decreases to zero

B. Total energy decreases

C. Both A. and B.

D. Flow pressure approaches its vapor pressure at the prevailing temperature
227. Water hammer in a pipeline results from the____________________?
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A. Pressure increase due to closure of a valve resulting in decrease in rate of flow

B. Bursting of pipelines due to closure by a valve

C. None of these

D. Rapid pressure change due to a rapid change in the rate of flow
228. The valve used for very remote and accurate control of fluid is a _____________ valve?
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A. Gate

B. Butterfly

C. Globe

D. Needle
229. Normal depth in open channel flow is the depth of flow in the channel ____________________?
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A. Measured normal to the channel bed

B. Corresponding to uniform flow

C. None of these

D. Corresponding to steady flow

230. A mixed flow centrifugal pump_______________________?
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A. Employs such an impeller, through which the flow is a combination of radial & axial flow

B. Mixes the two fluids before pumping them

C. Pumps the two fluids separately and then mixes them

D. Employs impellers in both the radial & axial directions

231. Drag co-efficient for motion of spherical particles in a stationary fluid in the stokes law range is_________________?
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A. 64/NRe,P

B. 48/NRe,P

C. 16/NRe,P

D. 24/NRe,P
232. The fluid in which the shearing stress within it is proportional to the velocity gradient across the sheared section, is called a _____________ fluid?
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A. Bingham

B. Newtonian

C. Perfect

D. None of these

233. A fluid is the one, which___________________?
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A. Permanently resists distortion

B. Is incompressible

C. Cannot remain at rest under the action of shear force

D. Continuously expands till it fills any container

234. 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____________________?
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A. Q/2

B. Q/16

C. Q/4

D. Q/8

235. Which of the following conditions must be satisfied for lift force to be developed ?
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A. Circulation around the body is essentially required

B. The body should be stream lined

C. The main stream velocity must approach the velocity of sound in that fluid medium

D. The body should be bluff body

236. Brownian movement is prominent in the particle size range of _____________ microns in case of settling of a particle in a fluid?
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A. 2 to 3

B. 0.01 to 0.10

C. 100 to 1000

D. 200 to 300

237. With increase in temperature, the vapor pressure of liquids__________________?
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A. Increases

B. Increases linearly

C. Remain constant

D. Decreases

238. For an incompressible fluid, the bulk modulus of elasticity is____________________?
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A. 0 N/m

B. 5 kg/m3

C. ? N/m2

D. 1 N

239. Mach number is defined as the ratio of the local flow velocity to the sonic velocity in the fluid. For what value of Mach number, the gases are considered incompressible ?
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A. > 3

B. 1

C. < 0.3

D. 50

240. Weber number is the ratio of inertial force to _____________ force?
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A. Viscous

B. Elastic

C. Gravity

D. Surface tension
241. Mass velocity is independent of temperature & pressure, when the flow is______________________?
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A. Steady and the cross-section is unchanged

B. Unsteady and the cross-section is changed

C. Steady through changing cross-section

D. Unsteady through unchanged cross-section

242. 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?
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A. Hyperbola

B. Semi-circle

C. Semi-ellipse

D. Parabola
243. Prandtl number is a measure of the__________________?
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A. Inertial force to elastic force in the fluid flow

B. Cp/Cv of a fluid

C. Elastic force to pressure force in the fluid flow

D. Heat conduction to viscosity of a fluid
244. Design of the casing of centrifugal pump should be such as to minimise the________________?
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A. Back flow through impeller

B. None of these

C. Loss of kinetic head

D. Loss of static head

245. Ratio of inertial forces to surface tension forces is called the _____________ number?
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A. Weber

B. Euler

C. Froude

D. Mach

246. In case of Couette flow, the fluid flow is between two large flat parallel plates with___________________?
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A. Top plate moving and the bottom plate fixed

B. Bottom plate moving and the top plate fixed

C. Both the plates fixed

D. Both the plates moving

247. For a given Reynolds number, in a hydraulically smooth pipe, further smoothening ____________ the friction factor?
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A. Brings about no further reduction of

B. Decreases

C. Increases

D. None of these

248. The energy loss in flow through Venturimeter is less than that through flow nozzle, because in case of a flow nozzle, the ?
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A. Distance between the throat and the inlet is more

B. Sudden expansion of flow in the downstream occurs

C. Length is shorter

D. Throat diameter is more

249. Hydraulic mean radius for flow through packed bed of spherical particle of size, Dp, with porosity ? is________________?
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A. (Dp/6) (?/1- ?)

B. ?Dp (?/1- ?)

C. (Dp/6) (1- ?/?)

D. ?Dp (1- ?/?)

250. Boundary layer exists in flow_________________?
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A. Of real fluids

B. Over flat surfaces only

C. Of ideal fluids only

D. In pipes only