chemical engineering process control and instrumentation Mcqs
301. Phase margin is equal to_______________?
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A. Phase lag 180

B. Phase lag + 180

C. 180 phase lag

D. Phase lag + 90

302. Which of the following cannot measure a temperature of 1600C ?
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A. Platinum resistance thermometer

B. Radiation pyrometer

C. Thermocouple

D. Photo-electric pyrometer

303. Working principle of mercury in glass thermometer is__________________?
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A. Linear expansion

B. Pressure rise with temperature

C. Volumetric expansion

D. None of these

304. Continuous flue gas analyser makes use of paramagnetic properties of some of its constituents, which move towards the strongest part of the magnetic field thus displacing diamagnetic gases. Which of the following gases is diamagnetic ?
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A. NO2

B. NO

C. CO2

D. O2

305. In a closed loop system, the process to be controlled is an integrating process with transfer function 1/2s. The controller proposed to be used in an integral controller with transfer function 1/T1s. When a step change in set point is applied to such a closed loop system, the controlled variable will exhibit__________________?
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A. Unstable response

B. Overdamped response

C. Underdamped response

D. Undamped response

306. For the time domain function f(t) = t, the Laplace transform of ?0 t f(t) dt is given by___________________?
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A. 2/S3

B. 1/2 S3

C. 1/S3

D. 2/S2

307. Which of the following filled system expansion thermometers has the lowest positive temperature measurement capability ?
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A. Fused metal (Na or K) in steel thermometer

B. Alcohol in glass thermometer

C. Nitrogen in steel thermometer

D. Mercury in glass thermometer

308. Pick out the wrong statement ?
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A. Proportional controller is normally used for level control in industrial applications

B. CSTR can be considered as a distributed parameter system

C. Non-linear behaviour is exemplified by an on-off controller

D. Distributed parameter approach gives partial differential equation

309. The transfer function for a P-D controller is________________?
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A. Kc ?D s

B. Kc(1 +1/?D s)

C. Kc/?D s

D. Kc(1+?D s)
310. Pick out the first order system from among the following ?
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A. Mercury in glass thermometer kept in boiling water

B. Interacting system of two tanks in series

C. Non-interacting system of two tanks in series

D. Damped vibrator

311. Pick out the one which is a first order instrument ?
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A. Mercury in glass thermometer (without any covering or air gap)

B. Bare metallic thermometer

C. All A., B. and C.

D. Bare vapor pressure thermometer

312. Select the correct statement from the following?
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A. The phase lag of a pure time delay system decreases with increasing frequency

B. The amplitude ratio of a pure capacity process is inversely proportional to frequency

C. The frequency response of a pure capacity process is unbounded

D. The amplitude ratio of a pure time delay system increases with frequency

313. All the thermocouples used for temperature measurement use dissimilar metal ________________?
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A. Wires

B. Bars

C. Strips

D. Beads

314. The root locus plot of the roots of the characteristics equation of a closed loop system having the open loop transfer function K (s + 1)/[2 (2s + 1) (3s + 1)] will have a definite number of loci for variation of K from 0 to ?. The number of loci is_______________?
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A. 2

B. 3

C. 4

D. 1

315. A non-linear chemical system is exemplified by a/an_________________?
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A. Mixer

B. Non-isothermal CSTR

C. Isothermal CSTR

D. None of these

316. Pick out the wrong statement?
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A. There is no transfer lag for a single first order system

B. Stirred tank with a water jacket exemplifies an interacting system

C. Transfer lag is a characteristic of all higher order systems (other than first order systems)

D. Transfer lag decreases as the number of stages decreases
317. The time taken for a radioactive element to reduce to 50% of its original weight is _____________ years, if its half life period is 12 years?
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A. 6

B. 18

C. 24

D. 36

318. A typical example of a physical system with under damped characteristic is a____________________?
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A. Thermocouple kept immersed in a liquid filled thermowell

B. CSTR with first order reaction

C. U-tube manometer

D. Spring loaded diaphragm valve
319. Thermocouple is suitable for measuring_________________?
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A. Liquid temperatures only

B. Very high temperatures only

C. Very low temperatures only

D. Both high and low temperatures
320. Dead zone is the__________________?
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A. Same as time constant

B. Maximum change in the variable that does not change the reading of the instrument

C. Same as transportation lag

D. None of these