chemical engineering process control and instrumentation Mcqs
251. The transfer function for a PID controller is (where, ? i is the integral (reset) time and ?D is the derivative time.) ?
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A. Kc(1 + ?is + (1/?D . s)

B. None of these

C. Kc[1 + (1/?is) + ?D . s)

D. Kc(1 + ?is + ?D ). s

252. Photoelectric pyrometers are suitable in the temperature range of ________________ C?
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A. 800-2500

B. 400-1600

C. 800-1600

D. 400-1000

253. What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple ?
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A. 29

B. 13

C. 3

D. 0.1

254. Temperature of molten pig iron (1450C) and molten slag (1500C) flowing out of a blast furnace is measured by a/an_______________?
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A. Optical pyrometer

B. Chromel-alumel thermocouple

C. Either B. or C.

D. Radiation pyrometer

255. Which of the following is a desirable characteristic of an instrument ?
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A. High drift

B. Poor reproducibility

C. High measuring lag

D. High fidelity
256. Cascade control means _______________?
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A. One feed-back loop

B. More than one feed-back loop

C. Feed forward control

D. On-off control

257. A mercury barometer measures the _____________ pressure?
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A. Absolute

B. Vacuum

C. Gauge

D. Atmospheric
258. Working principle of radiation pyrometer is based on the __________________?
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A. Stefan Boltzmann law

B. Wiens law

C. Seebeck effect

D. Kirchoffs law

259. Liquid column manometers are used for measuring the pressure ______________ kgf/cm2?
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A. < atmospheric

B. < 10 (gage)

C. > 2 (gage)

D. < 3 (gage)
260. The frequency response of a dynamic element shows a constant magnitude ratio at all frequencies. The element exhibits a negative phase shift at all frequencies. The absolute value of the phase shift increases linearly with frequency. The element has the transfer function ?
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A. (T1S + 1)/(T2S

B. (T1S/(T2S + 1)

C. (T1S + 1)/(T2S + 1)

D. e-?S
261. Which of the following controllers has the least maximum deviation ?
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A. P-controller

B. P-D controller

C. P-I controller

D. P-I-D controller

262. The characteristic equation for the control system with a closed loop transfer function G1/1 + G2 is given by 1 + G2 = 0. The characteristic equation for the control system_________________?
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A. Depends only upon the open loop transfer function

B. Is the same for set point or load changes

C. All A , B & C.

D. Determines its stability

263. The level of a liquid under pressure can be determined using___________________?
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A. Differential pressure manometer

B. Diaphragm box system

C. Bubbler system

D. Air-trap system

264. Characteristic equation is the denominator of ____________ loop transfer function?
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A. Open

B. Closed

C. Both A. and B.

D. Neither A. nor B.

265. Which of the systems having following transfer functions is stable ?
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A. 1/(s2 + 2s + 2)

B. exp (-20s)/(s2 + 2s 1)

C. 1/(s2 + 2)

D. 1/(s2 2s + 3)

266. A first order system with unity gain and time constant ? is subjected to a sinusoidal input of frequency w = 1/?. The amplitude ratio for this system is______________?
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A. 1/?2

B. 1

C. 0.25

D. 0.5

267. Liquid flow rate in a small channel is best measured by a/an____________________?
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A. Venturimeter

B. Weir

C. Vane meter

D. Pitot tube
268. Sub-zero temperature (< 0C) can be measured by a constant volume gas thermometer employing ?
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A. Nitrogen

B. Helium

C. Hydrogen

D. None of these

269. Dilute wine was used as a thermometric liquid initially to develop temperature scale. First empirical temperature scale developed was the _____________ scale?
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A. Kelvin

B. Fahrenheit

C. Reaumer

D. Centigrade

270. Turbine flow meters are suitable for_________________?
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A. Very limited flow ranges

B. Cryogenic flow measurements

C. Aerospace and in air borne applications

D. Both B. and C.
271. Resistance of a gas in a vessel is given by (where, P = pressure, V = volume of the vessel, n = no. of moles of the gas, R = gas constant) ?
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A. P/nRT

B. nRT/P

C. nRT/V

D. V/nRT
272. Compositional analysis of ______________ is done using mass spectrometer?
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A. An isotope

B. Natural gas

C. An alloy

D. A solid

273. Silver point temperature is ______________ C?
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A. 860.5

B. 760.5

C. 1060.5

D. 960.5
274. The amplitude ratio for the sinusoidal response of __________ is < 1?
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A. First order system

B. Second order system

C. None of these

D. Transportation lag

275. With increase in temperature, the electrical conductivity of the platinum used in the resistance thermometer ?
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A. Remain constant

B. Increases

C. Increases exponentially

D. Decreases
276. Time constant is the __________________?
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A. Same as transportation lag

B. Time required by the measured variable to reach 63.2% of its ultimate change

C. Same as dead time

D. Time taken by the controlled variable to reach 63.2% of its full change
277. What is the Laplace transform of sin t ?
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A. s/(s2 1)

B. s/(1 + s2)

C. 1/(s2 1)

D. 1/(s2 + 1)
278. The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ C?
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A. 250

B. 500

C. 750

279. Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a __________________?
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A. Vapor pressure thermometer

B. Thermocouple

C. Resistance thermometer

D. Mercury in glass thermometer

280. Flow rate of a river is measured by a/an____________________?
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A. Pitot tube

B. Open weir

C. Kennison nozzle

D. Vane meter
281. Configuration of Bourdon spring tube is never made of _____________ shape?
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A. Circular

B. Semi-circular

C. Helical

D. Spiral

282. A system with transfer function [(2S/4S) + 1] is of _____________ order?
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A. 2nd

B. 3rd

C. Zero

D. 1st
283. Thermal conductivity measurement com-prises the working principle of a_________________?
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A. CO2 analyser

B. Spectrometer

C. Polarimeter

D. Chromatograph

284. Which of the following is not classified as a thermo electric pyrometer ?
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A. Resistance thermometer

B. Optical pyrometer (disappearing filament type)

C. Thermocouple

D. Radiation pyrometer

285. Hot wire anemometer is used for the measurement of___________________?
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A. Flow rates of granular solids

B. Thermal conductivity of gases

C. Very high temperature

D. Flow rates of fluids
286. Continuous measurement of specific gravity of a liquid is done by __________________?
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A. Hydrometer

B. Contact-type electric indicators

C. Displacement meter

D. Both A. and C.
287. Bode stability method uses ____________ loop transfer function?
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A. Neither A. nor B.

B. Open

C. Closed

D. Either A. or B.

288. An amplitude ratio of 0.1 corresponds to _____________ decibels?
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A. -10

B. 20

C. 10

D. -20
289. _______________ thermometer cannot measure sub-zero (< 0 C) temperature ?
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A. Mercury in glass

B. Resistance

C. Vapor pressure

D. Bimetallic
290. Radiation pyrometers as compared to thermocouples____________________?
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A. Cant measure the temperature of moving objects

B. Is more affected by corrosive atmosphere

C. Has a slower speed of response

D. Can measure higher temperature
291. Continuous measurement of moisture content of paper in paper industry is done by measuring the_________________?
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A. Electrical resistance through the paper

B. Magnetic susceptibility

C. Thermal conductivity through the paper

D. None of these

292. Which of the following measurements can be made by the measurement of emf ?
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A. All A., B. & C.

B. Composition of complex ions

C. Degree of hydrolysis

D. pH value

293. A bimetallic thermometer as compared to industrial mercury in glass thermometer has almost the same_________________?
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A. Speed of response

B. Temperature measuring range (- 40C to 450C)

C. Accuracy ( 1% of span)

D. All a, b & c
294. Thermocouple in a thermal well behaves as a true ________________?
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A. Second order system (overdamped)

B. Multiple first order system

C. Second order system (underdamped)

D. First order system

295. The unit step response of the transfer function 1/(s2 + 2s + 3) _______________________?
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A. Has a non-zero slope at the origin

B. Is overdamped

C. Has a damped oscillatory characteristics

D. Is unstable

296. In a second order under damped system, the_________________?
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A. h the decrease of damping co-efficient</strong>

B. None of these

C. Decay ratio (which is the ratio of the sizes of successive peaks) is equal to the reciprocal of

D. Overshoot (which is a measure of how much the response exceeds the ultimate value) increase

E. rshoot

F. Time required for the response of first reach its ultimate value is called the response time

297. A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency. This is _______________ criterion?
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A. Nyquist

B. None of these

C. Routh stability

D. Bode stability
298. The frequency at which maximum amplitude ratio is attained is called the ______________ frequency?
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A. Natural

B. Corner

C. Cross-over

D. Resonant
299. The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60, then the dead time (in minutes) is________________?
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A. ?/12

B. ?/3

C. ?/6

D. 5?/12
300. Water is entering a storage tank at a temperature T0 and flow rate Q0 and leaving at a flow rate Q and temperature T. There are negligible heat losses in the tank. The area of cross-section of the tank is A0. The model that describes the dynamic variation of temperature of water in the tank with time is given as________________?
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A. Q(T0 T) = Ac . h (dT/dt)

B. Q0(T0 T) = Ac . h (dT/dt)

C. Q0T0 QT = Ac . h (dT/dt)

D. Q(T0 T) = Ac . (dTH/dt)