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chemical engineering process control and instrumentation MCQs

Practise multiple-choice questions from chemical engineering process control and instrumentation for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering process control and instrumentation Mcqs
1. On-off control which is a special case of proportional control, has a band width of about _____________ percent?
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A. 75

B. 0

C. 25

D. 100

2. The transfer function for an ideal proportional plus reset controller (reset time T) is_______________?
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A. Kc(1 + TS)

B. Kc/[1 + (s/T)]

C. Kc/(1 + TS)

D. Kc[1 + (1/TS)]
3. Which of the following thermocouples has the least temperature measurement range ?
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A. Copper-constantan

B. Chromel-alumel

C. Iron-constantan

D. Platinum-platinum/rhodium

4. The inverse Laplace transform of the function f(S) = 1/S (1 + S) is_________________?
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A. 1 e-t

B. 1 + et

C. 1 et

D. 1 + e-t

5. Identify an unbounded input from inputs whose transfer functions are given below______________?
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A. 1

B. 1/(S2 + 1)

C. 1/S2

D. 1/S

6. Thermistors are made of__________________?
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A. Nickel-chromium alloys

B. Iron-copper alloys

C. Ultra pure metals

D. Metal oxides
7. A system with a double pole at the origin is unstable since the corresponding term in the time domain________________?
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A. Grows linearly with time

B. Decays linearly with time

C. Is a constant

D. Grows exponentially with time

8. Vapour actuated pressure spring thermometer does not require ambient temperature compensation. Ambient temperature compensation is provided in gas or liquid expansion pressure spring thermometer by__________________?
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A. All A , B & C.

B. Making the volume of thermometer bulb as large as conveniently possible

C. Reducing the volume of the receiving element to a minimum

D. Reducing the volume of the capillary to a minimum

9. A non-linear system will have _____________ steady state values?
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A. One

B. Two

C. Three

D. More than one
10. A barometer measures the _____________ pressure?
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A. Absolute

B. Gauge

C. Absolute as well as gauge

D. dynamic

11. Platinum resistance thermometer can be used upto antimony point which is ____________ C, and is the temperature of equilibrium between solid antimony & liquid antimony at normal atmospheric pressure?
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A. 1261.93

B. 1064.43

C. 961.93

D. 630.74
12. Composition of alloys can be determined by _________________?
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A. Polarograph

B. Refractometer

C. None of these

D. Chromatograph

13. A photo electric device in which the resistance of the metal is directly proportional to the light striking on it, is known as photo-conductive cell. Photoelectric transducers are used for the measurement of those parameters, which can be used to produce variation in_______________?
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A. Current

B. Voltage

C. Flux density

D. Light intensity
14. Normal mercury thermometer can be used to measure a temperature of about 300C. However, its maximum temperature measurement range can be increased upto about 500C by__________________?
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A. Filling nitrogen under pressure in the stem

B. Accounting for the tube expansion

C. Using steel tube in place of glass tube

D. Increasing the diameter of the tube

15. A sinusoidal variation in the input passing through a linear first order system _________________?
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A. Gets attenuated (magnitude decreases)

B. Becomes more oscillatory (frequency increases)

C. Gets amplified (magnitude increases)

D. Becomes less oscillatory (frequency decreases)

16. Working principle of mercury in glass thermometer is based on the ______________ of mercury with increase in temperature?
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A. Volumetric expansion

B. Increase of pressure

C. Differential linear expansion

D. Increase of thermal conductivity

17. A bolometer is __________________?
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A. Used for the measurement of thermal radiation

B. An element which senses optical input and delivers thermal output

C. Both A. & B.

D. Neither A. nor B.

18. Concentration of sugar solution can be determined by the__________________?
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A. Oscillometry

B. Flame photometry

C. Emission spectroscopy

D. Polarimetry
19. Mercury thermometer can be used to measure the temperature upto ____________ C?
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A. 350

B. 250

C. 100

D. 750

20. A pyranometer is an instrument used for measuring the___________________?
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A. Beam radiation

B. Bright sunshine period

C. None of these

D. Global radiation
21. Bode diagram are generated from output response of the system subjected to which of the following input ?
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A. Step

B. Sinusoidal

C. Impulse

D. Ramp

22. In a single tank system, the transfer function of _____________ to inlet flow rate is 1/(TS+1)?
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A. Outlet flow rate

B. Level

C. Both A. & B.

D. Neither A. nor B.

23. A constant volume gas thermometer employing ______________ is used to measure sub-zero (i.e., < 0C) temperature?
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A. Hydrogen

B. None of these

C. Helium

D. Nitrogen

24. Nitrogen gas constant volume thermometer is suitable for measuring a temperature of _____________ C?
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A. 0-100

B. > 50

C. < 0

D. > 100
25. Gas chromatography is used for the measurement of ________________?
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A. Pressure

B. Concentration

C. Temperature

D. Flow rate

26. Stabilising time for the controllers is the time required for the response to reach _____________ percent of its ultimate value?
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A. 95

B. 63.2

C. 87.5

D. 100

27. Working principle of disappearing filament type optical pyrometer is based on the ________________?
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A. Peltier effect

B. Kirchoffs law

C. Seebeck effect

D. Wiens law
28. Which of the following does not figure in the list of seven substances selected for international temperature scale ?
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A. Antimony and silver (F.P)

B. Oxygen and sulphur (B.P)

C. Ice (F.P) and steam (B.P)

D. Zinc (B.P) and mercury (F.P)
29. Very low pressure is expressed in microns (?), which is equal to ____________ mm of Hg column (absolute) at 0C?
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A. 0.01

B. 0.1

C. 0.001

D. 0.0001

30. The frequency response of a first order system, has a phase shift with lower and upper bounds given by________________?
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A. -?/2, ?/2

B. ?, ?/2

C. 0, ?/2

D. -?/2, 0

31. The transfer function of a first order system is______________?
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A. 1/Ts

B. s/(Ts + 1)

C. None of these

D. 1/(Ts + 1)
32. In a feed-back control system G and H denote open loop and close loop transfer functions respectively. The output-input relationship is_____________?
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A. H/G

B. G/(1 + H)

C. H/(1 + G)

D. G/H

33. Mcleod gauge is used to measure the __________________?
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A. Point velocity

B. Pressure

C. Vacuum

D. Flow rate

34. Measurement of pressure in ammonia reactor is done by __________________?
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A. Pirani gauge

B. U-tube manometer

C. Bourdon gauge

D. Inclined tube manometer

35. The Laplace transform of exp(at), where a > 0, is defined only for the Laplace parameter, s > a since______________?
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A. The Laplace transform of integral of exp(at) has finite values only for s > a

B. The function exp(at) is piece-wise continuous only for s > a

C. The Laplace transform integral of exp(at) has initial values only for s > a

D. The function is exponential

36. What is the overall transfer function (C/R) of the following block diagram if G = G1. G2. G3 and H = H1.H2 ?
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A. H/(1 + GH)

B. G/(1 GH)

C. G/(1 + GH)

D. 1/(1 + GH)

37. Dilatometer is used to measure __________________?
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A. Deflection

B. Contraction/expansion due to changes in temperature

C. Stress

D. Strain

38. The time constant of a first order process with resistance R and capacitance C is__________________?
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A. RC

B. R + C

C. R C

D. 1/RC

39. Change of angle of refraction with composition comprises the working principle of a___________________?
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A. Spectrometer

B. Polarimeter

C. Refractometer

D. Polarograph

40. Find the ultimate gain and frequency for a proportional controller in the case of a process having the transfer function Gp(s) = 1/(4s + 1)(2s + 1)(s + 1) ?
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A. w = 1/?14, Kc = 45/7 ?14

B. w = ?(7/6), Kc = 46/3

C. w = ?(7/8), Kc = 45/4

D. w = 1, Kc = 13

41. The initial value (t = 0) of the unit step response of the transfer function [(s + 1)/(2s + 1)] is__________________?
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A. 0

B.

C. 2

D. 1

42. Temperature of _____________ cannot be measured by an optical or radiation pyrometer?
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A. Rotary limestone calcination kiln

B. Combustion space in boilers

C. Molten slag flowing out of blast furnace

D. Hot blast (air) from stoves
43. Relationship between absorption/evolution of heat at the thermocouple junctions and the current flow in the circuit is given by _____________ effect?
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A. Thomson

B. Seebeck

C. None of these

D. Peltier
44. Radiation thermometer cannot measure the temperature ___________________?
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A. Of liquid oxygen

B. Inside a pressure vessel

C. Of an object without coming in contact with it

D. Of moving objects at high temperature

45. Zirconia probe is used for the continuous measurement of ______________ flue gases going out of the furnace?
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A. Oxygen in

B. Temperature of

C. Carbon monoxide in

D. Carbon dioxide in

46. The root locus method, a pole of a transfer function G(s) is the value of s for which G(s) approaches ___________________?
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A. ?

B. 1

C. -1

D. 0

47. Liquid levels in autoclaves are measured by ________________?
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A. None of these

B. Differential float type manometer

C. Simple float

D. Glass gauge

48. When the damping co-efficient (?) is unity, the system is __________________?
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A. Underdamped

B. Critically damped

C. Overdamped

D. Highly fluctuating

49. Optical activity of a solution can be determined using a ___________________?
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A. Dilatometer

B. Polarograph

C. Polarimeter

D. Refractometer

50. Specific conductance is defined as the reciprocal of resistance in ohms of 1c.c. of liquid at a specified temperature. Its value for distilled water is about ______________ micro mho/cm3?
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A. 100

B. 50

C. 1

D. 10