chemical engineering process control and instrumentation Mcqs
201. Paramagnetism method is not used for the composition determination of ______________ in gases?
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A. Carbon dioxide

B. Oxides of nitrogen

C. Oxygen

D. Any of these

202. The experimental response of the controlled variable y(t) for a step change of magnitude P in the manipulated variable x(t) is shown below: The appropriate transfer function of the process is_________________?
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A. (Q/R) e-TdS/(Q/P) (S + 1)

B. (Q/P) e-TdS/(Q/R) (S + 1)

C. (Q/P) e-(Q/R)S/(TdS + 1)

D. (Q/R) e-(P/Q)S/(TdS + 1)

203. The term analogous to the electrical current in a thermal system is the_________________?
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A. Temperature difference

B. Heat content in the system

C. Heat flow rate

D. None of these

204. Load cells are used for the measurement of __________________?
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A. Weight

B. Velocity

C. Stress

D. Strain

205. Number of poles in a system with transfer function 1/(s2 + 2s2 + 1) is ________________?
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A. 1

B. 3

C. 2

D. 5

206. Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature ?
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A. Platinum-platinum + rhodium

B. Iron-constantan

C. All will give the same output

D. Chromel-constantan
207. The open loop transfer function of a process is K [{(s + 1) (s + 4)}/{(s + 2) (s + 3)}]. In the root locus diagram, the poles will be at ___________________?
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A. 2, 3

B. -2, -3

C. 1, 4

D. -1, -4

208. Pyrometry refers to the measurement of temperature_________________?
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A. Directly

B. Which is of higher magnitude

C. With the mercurial thermometer upto 350C

D. All A., B. & C.

209. Response of a linear control system for a change in set point is called __________________?
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A. Transient response

B. Servo problem

C. Regulator problem

D. Frequency response

210. On-off controllers are normally used for________________?
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A. None of these

B. Flow rate changes

C. Temperature changes

D. Low loads
211. To increase the speed of response of a pressure spring liquid or gas expansion thermometer, the clearance space between the thermometer bulb and the thermal well should not be filled with ________________?
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A. Air

B. A metal powder or graphite

C. Mercury

D. Oil

212. Flow rate of those fluids which are insensitive to changes in their density, viscosity or flow velocity profile can be best measured by a ________________?
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A. Magnetic flowmeter

B. Turbine flowmeter

C. Flow nozzle type flowmeter

D. Pitot tube

213. Which of the following fluid flow measuring devices can measure the largest flow rate ?
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A. Orificemeter

B. Weir

C. Rotameter

D. V-notch

214. In an exothermic chemical reactor, the manipulated variable is the flow rate of_______________?
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A. Product

B. Reactants

C. Coolant

D. None of these

215. For an input forcing function, X(t) = 2t2, the Laplace transform of this function is________________?
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A. 4/s2

B. 2/s2

C. 4/s3

D. 2/s3

216. The open loop transfer function of a control system is KR/(1 + TS). This represents ______________?
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A. A second order system

B. Dead time system

C. A first order time lag

D. A first order system
217. Which of the following can measure temperatures in the range of 20 to 300C ?
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A. None of these

B. Vapor pressure thermometer

C. Resistance thermometer

D. Mercury in glass thermometer

218. In a single tank system, the transfer function of level to inlet flow rate is__________________?
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A. R/(TS + 1)

B. 1/TS

C. R/TS

D. None of these

219. What is the Laplace transform of impulse input having magnitude X? ?
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A. 1/X

B. 1

C. X

D. X2

220. Emf developed by a thermocouple while measuring a temperature of 400C is 22 mV. The type of thermocouple used is ___________________?
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A. Platinum-rhodium

B. Iron-constantan

C. Chromel-alumel

D. Platinum-platinum + rhodium

221. Thermodynamic Celsius scale of temperature measurement is________________?
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A. Defined on the basis of melting point of ice and evaporation temperature of water vapor

B. Defined on the basis of melting point of ice and condensation temperature of water vapor

C. Having an interval of 100 between ice point to steam point

D. Both B. and C.
222. Response of a system to a sinusoidal input is called _____________ response?
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A. Frequency

B. Impulse

C. Unit step

D. None of these

223. Helium gas constant volume thermometer is suitable for the measurement of a temperature of ______________ C?
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A. < 0

B. > 0

C. > 800

D. < 100

224. Gain margin is equal to the_________________?
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A. Reciprocal of amplitude ratio

B. Gain in P controller

C. Amplitude ratio

D. Gain in P-I controller

225. A negative gain margin expressed in decibels means a/an ____________ system?
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A. Unstable

B. Critically damped

C. None of these

D. Stable

226. Accurate temperature measurement performance of a radiation pyrometer cannot be affected, if the ?
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A. Object has varying emissivity

B. Enhancement or attenuation of radiation occurs in the sighting path

C. Object and surrounding are at almost the same temperature

D. Object is transparent

227. For a feed back control system to be stable, the _________________?
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A. Poles of the closed loop transfer function should lie in the left half of the complex plane

B. Poles of the closed loop transfer function should lie in the right half of the complex plane

C. Roots of the characteristic equation should be real

D. Bode plots of the corresponding open loop transfer function should monotonically decrease

228. E.m.f. generated by thermocouples is of the order of ________________?
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A. Volts

B. Milli volts

C. Micro volts

D. Kilo volts

229. Temperature measuring instruments are standardised mostly with _____________ points of pure substances?
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A. Melting

B. Boiling

C. Both A. & B.

D. Neither A. nor B.

230. Which of the following is the dynamic characteristics of an instrument ?
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A. Fidelity

B. Sensitivity

C. Reproducibility

D. Dead zone

231. In Bode plot, A.R. vs. w is plotted on a/an _____________ graph paper?
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A. Ordinary

B. Semi-log

C. Triangular

D. Log-lag
232. A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if________________?
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A. Integral control action is introduced

B. Derivative control action is introduced

C. Kc is increased

D. Kc is reduced

233. Which of the following thermocouple materials does not contain nickel ?
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A. Constantan

B. None of these

C. Chromel

D. Alumel

234. Thermal conductivity measurement is used for the determination of________________?
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A. Specific gravity of petrofuels

B. O2 percentage in the flue gas

C. CO2 percentage in the flue gas

D. Composition of an alloy

235. Thermal wells are used in the temperature measurement to____________________?
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A. Increase the sensitivity

B. Increase the fidelity

C. Reduce measuring lag

D. Guard against corrosive and oxidising action on thermocouple materials
236. Nickel percentage in invar which is an iron-nickel alloy, and is used as a thermocouple material is __________________?
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A. 68

B. 36

C. 12

D. 54

237. A mercury thermometer cannot be used to measure the temperature below the freezing point of mercury, which is _____________ C?
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A. -80.9

B. -11.9

C. -60.9

D. -38.9
238. In a shell and tube heat exchanger, the inlet temperature of heating/cooling fluid is the ____________ variable?
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A. Manipulated

B. Controlled

C. None of these

D. Load
239. The ____________ of the fluid contained in the temperature sensing element (i.e., bulb) of filled system thermometers changes with change in temperature ?
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A. Volume

B. Pressure

C. Viscosity

D. All A., B. and C.
240. The operation of a Rotameter is based on ________________?
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A. Variable flow area

B. Rotation of a turbine

C. Pressure drop across a nozzle

D. Pressure at a stagnation point

241. Temperature control of an exothermic chemical reaction taking place in a CSTR is done with the help of cooling water flowing in a jacket around the reactor. The types of valve and controller action to be recommended are________________?
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A. Air to close valve with the controller direct acting

B. Air to open valve with the controller indirect acting

C. Air to open valve with the controller direct acting

D. Air to close valve with the controller indirect acting

242. Routh stability method uses ______________ loop transfer function?
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A. Open

B. Closed

C. Neither A. nor B.

D. Either A. or B.

243. Dome temperature of blast furnace stove is most accurately measured by a____________________?
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A. Platinum resistance thermometer

B. Iron-constantan thermocouple

C. Radiation pyrometer

D. platinum-platinum/rhodium thermocouple
244. For increased speed of response of an expansion pressure spring thermometer, the thermometer bulb should have a__________________?
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A. High thermal conductivity

B. Large area but small mass

C. Small specific heat

D. All A , B & C
245. Liquid flow rate in an open channel cannot be measured by a/an __________________?
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A. Rectangular weir

B. V-notch

C. Cipolletti weir

D. Orifice meter
246. Which of the following shows maximum dip effect (indicating reverse direction of temperature change) ?
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A. Radiation pyrometer

B. Thermocouple

C. Bimetallic thermometer

D. Mercury thermometer
247. Compositional analysis of flue gas coming out of a furnace in respect of O2 and CO2% can be continuously done by a/an___________________?
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A. Thermal conductivity cell

B. Orsat apparatus

C. Chromatograph

D. Zirconia probe

248. Use of I-control along with P-control facilitates ?
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A. None of these

B. Reduction of stability time

C. Reduction of offset

D. Elimination of offset
249. Thermistors which have a very high temperature co-efficient of resistivity belong to the class of solid called________________?
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A. Dielectrics

B. Conductors

C. Insulators

D. Semi conductors
250. _____________ is an example of distributed parameter system ?
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A. Tubular reactor

B. None of these

C. CSTR

D. On-off controller