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Process Control and Instrumentation Flashcards

1
Q

Which of the following is an undesirable dynamic characteristic of an instrument ?

A

Time lag

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2
Q

Which of the following is not the triple point of water ?

A

32°R

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3
Q

Pick out the one which is a first order instrument.

A

All (a), (b) and (c).

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4
Q

Load cells are used for the measurement of

A

weight

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5
Q

Which of the following is the dynamic characteristics of an instrument ?

A

Fidelity

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6
Q

Pick out the wrong statement.

A

CO2 is the strongest paramagnetic gas.

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7
Q

The __________ of a vapor pressure thermometer is a functioning element.

A

pointer

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8
Q

A negative gain margin expressed in decibels means a/an __________ system.

A

unstable

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9
Q

Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an

A

solid semi-conductor

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10
Q

Flapper nozzle is used in a/an __________ controller.

A

pneumatic

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11
Q

Typical specifications for design stipulates the gain margin and phase margin to be respectively

A

> 1.7 and > 30°

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12
Q

Working principle of radiation pyrometer is based on the

A

Stafan-Boltzman law

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13
Q

Which of the following relates the emf. generated in a single homogeneous wire to the temperature difference ?

A

Thomson effect

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14
Q

Dilute wine was used as a thermometric liquid initially to develop temperature scale. First emperical temperature scale developed was the __________ scale.

A

Fahrenheit

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15
Q

In a single tank system, the transfer function of level to inlet flow rate is

A

R/(TS + 1)

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16
Q

Which of the following is a desirable characteristic of an instrument ?

A

High fidelity

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17
Q

The operation of a rotameter is based on

A

variable flow area.

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18
Q

The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple.

A

iron-constantan

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19
Q

Instrumentation in a plant offers the advantage of

A

all (a), (b) and (c)

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20
Q

Which of the following temperature measuring instruments need not touch the object whose temperature is being measured ?

A

Radiation/infrared pyrometer

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21
Q

Thermal conductivity measurement com-prises the working principle of a

A

CO2 analyser

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22
Q

Response of a system to a sinusoidal input is called __________ response.

A

frequency

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23
Q

The closed loop pole of a stable second order system could be

A

both real and negative.

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24
Q

Smoke density of the flue gas going out of the chimney is measured by a

A

photo electric cell

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25
Q

Transfer function of transportation lag is

A

e-TS

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26
Q

Temperature measuring instruments are standardised mostly with __________ points of pure substances.

A

both (a) & (b)

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27
Q

Pick out the first order system from among the following.

A

Mercury in glass thermometer kept in boiling water.

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28
Q

The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ °C.

A

500

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29
Q

Which of the following controllers has the least maximum deviation ?

A

P-D controller

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30
Q

Volumetric expansion is the working principle of the __________ thermometers.

A

mercury in glass

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31
Q

Which of the following measurements can be made by the measurement of emf ?

A

All (a), (b) & (c)

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32
Q

A magnetic flowmeter is

A

all (a), (b) and (c).

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33
Q

Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.

A

oxygen in

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34
Q

Strain gage pressure transducers are used to measure __________ pressures.

A

both (a) and (b)

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35
Q

The transfer function for a PID controller is (where, τ i is the integral (reset) time and τD is the derivative time.)

A
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36
Q

Compositional analysis of __________ is done using mass spectrometer.

A

an isotope

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37
Q

The function of a transducer is to

A

convert the primary signal into a more useful quantity, usually an electric impulse.

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38
Q

Nichol’s chart deals with

A

closed loop values vs. open loop values.

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39
Q

Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature ?

A

Chromel-constantan.

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40
Q

A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if

A

Kc is reduced.

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41
Q

The symbol for “capillary line” in instrumentation diagram is

A
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42
Q

__________ is undesirable in thermocouples used in industries,

A

Non-linear relation of emf to temperature

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43
Q

Select the correct statement from the following.

A

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

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44
Q

For an input forcing function, X(t) = 2t2, the Laplace transform of this function is

A

4/s3

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45
Q

Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a

A

thermocouple

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46
Q

The __________ of a vapor pressure thermometer is a secondary element.

A

Bourdon tube

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47
Q

Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is

A

platinum-platinum+rhodium

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48
Q

Which of the following relates the absorption & evolution of heat at the junctions of a thermocouple to the current flow in the circuit?

A

Peltier effect

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49
Q

The second order system with the transfer function 4/s^2+2s+4 has a damping ratio of

A

0.5

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50
Q

In a shell and tube heat exchanger, the flow rate of heating/cooling fluid is the __________ variable.

A

manipulated

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51
Q

A non-linear chemical system is exemplified by a/an

A

non-isothermal CSTR

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52
Q

The transfer function for an ideal proportional plus reset controller (reset time T) is

A

Kc(1+ 1/TS)

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53
Q

The frequency response of a first order system, has a phase shift with lower and upper bounds given by

A

0, π/2

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54
Q

Gas chromatography is used for the measurement of

A

concentration

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55
Q

Which of the following thermocouples can measure the maximum temperature ?

A

Tungsten-molybdenum

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56
Q

Radiation pyrometers as compared to thermocouples

A

can measure higher temperature.

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57
Q

Liquid flow rate in a small channel is best measured by a/an

A

pitot tube

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58
Q

Specific gravity of a liquid can not be measured by a/an

A

anemometer

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59
Q

__________ temperature scale assigns 0° to the ‘ice point’ and 80° to the ‘steam point’.

A

Reumur

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60
Q

Dead zone is the

A

maximum change in the variable that does not change the reading of the instrument.

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61
Q

Which of the following thermometers is not suitable for distant reading upto 60 metres?

A

Mercury in glass thermometer

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62
Q

Degree to which an instrument indicates the changes in measured variable without dynamic error is called its

A

fidielity

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63
Q

Thermistors are made of

A

metal oxides

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64
Q

A barometer measures the __________ pressure.

A

absolute

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65
Q

Humidity of air can be determined by a

A

sling psychrometer

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66
Q

Thermocouple in a thermal well behaves as a true

A

multiple first order system.

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67
Q

The transfer function for a P-D controller is

A

Kc(1+τD s)

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68
Q

Bode diagram is a plot of

A

log (AR) vs. log (f) and (Φ) vs. log (f).

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69
Q

Working principle of disappearing filament type optical pyrometer is based on the

A

Wien’s law

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70
Q

Strain gage uses an electrical conductor wire, which when elastically stretched increases in length and reduces in diameter. Both these dimensional changes result in __________ in the electrical resistance of the wire.

A

increase

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71
Q

Pick out the wrong statement

A

CSTR can be considered as a distributed parameter system.

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72
Q

Range of hydrogen gas constant volume themometer is __________ °C.

A

0 to 100

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73
Q

The initial value (t=0) of the unit step response of the transfer function [(s + 1)/(2s + 1)] is

A

1/2

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74
Q

The __________ of a vapor pressure thermometer is a primary element.

A

bulb

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75
Q

The time constant of a first order process with resistance R and capacitance C is

A

RC

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76
Q

A sinusoidal variation in the input passing through a linear first order system

A

gets attenuated (magnitude decreases).

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77
Q

Nitrogen gas constant volume thermometer is suitable for measuring a temperature of __________ °C.

A

> 100

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78
Q

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

A

G/1+GH

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79
Q

Pick out the most suitable instrument for measuring temperature in the range of-40 to 425°C.

A

bimetallic thermometer

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80
Q

Accurate temperature measurement performance of a radiation pyrometer can not be affected, if the

A

object and surrounding are at almost the same temperature.

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81
Q

Relationship between absorption/evolution of heat at the thermocouple junctions and the current flow in the circuit is given by __________ effect.

A

Peltier

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82
Q

Configuration of Bourdon spring tube is never made of __________ shape.

A

circular

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83
Q

Thermodynamic celcius scale of temperature measurement is

A

both (b) and (c)

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84
Q

According to Bode stability criterian, a system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at frequency for which phase lag is

A

180°

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85
Q

In a closed loop system, the process to be controlled is an integrating process with transfer function l/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

A

underdamped response.

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86
Q

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)

A

V/nRT

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87
Q

Measurement of pressure in ammonia reactor is done by

A

Bourdon gauge

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88
Q

The fluid used in hydraulic controller is

A

oil

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89
Q

Flow rate of a river is measured by a/an

A

vane meter

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90
Q

Which of the following thermocouple materials does not contain nickel ?

A

None of these.

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91
Q

Flow rate of those fluids which are insensitive to changes in their density, viscosity or flow velocity profile can be best measured by a

A

magnetic flowmeter

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92
Q

Identify an unbounded input from inputs whose transfer functions are given below

A

1/S^2

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93
Q

“A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency.” This is __________ criterion.

A

Bode stability

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94
Q

Feed forward controller accounts for the __________ changes.

A

load

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95
Q

Which thermocouple can be used to measure a temperature of around 1400°C ?

A

Platinum-platinum+rhodium

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96
Q

Which of the following filled system expansion thermometer has the capability to measure the lowest temperature ?

A

Alcohol in glass thermometer

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97
Q

Concentration of sugar solution can be determined by the

A

polarimetry

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98
Q

In a single tank system, the transfer function of __________ to inlet flow rate is 1/TS+1.

A

outlet flow rate

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99
Q

Which of the following can not measure a temperature of 1600°C ?

A

Platinum resistance thermometer

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100
Q

The temperature range for which copper resistance thermometer can be used is __________ °C

A

-200 to 150

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101
Q

Paramagnetism method is not used for the composition determination of __________ in gases.

A

carbon dioxide

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102
Q

An amplitude ratio of 0.1 corresponds to __________ decibels.

A

-20

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103
Q

For increased speed of response of an expansion pressure spring thermometer, the thermometer bulb should have a

A

all’a’, ‘b’ & ‘c’.

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104
Q

Pressure of 0.0001 absolute psi can be measured by __________ gauge.

A

Mcloid

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105
Q

Pirani gauge is used for the measurement of

A

high vacuum.

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106
Q

The __________ of the fluid contained in the temperature sensing element (i.e., bulb) of filled system thermometers changes with change in temperature.

A

all (a), (b) and (c)

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107
Q

Transfer functions X/Y for which of the following block diagrams is

A
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108
Q

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

A

all ‘a’, ‘b’ & ‘c’

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109
Q

__________ thermometer can not measure sub-zero (< 0° C) temperature,

A

Bimetallic

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110
Q

Starting temperature of optical radiation pyrometer is __________ °C.

A

800

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111
Q

Liquid argon level in a pressurised storage tank (at 3 kg/cm2 ) is measured by a/an

A

differential pressure gage

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112
Q

Which of the systems having following transfer functions is stable?

A

1/(s2 + 2s + 2)

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113
Q

What is the dynamic error in a critically damped second order instrument for a ramp input (At) ?

A

2 AT

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114
Q

The transfer function for a first order process with time delay is

A
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115
Q

An ideal PID controller has the transfer function . The frequency at which the magnitude ratio of the controller is 1, is

A

1/sqrt(0.2 x 0.5)

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116
Q

The deflection of the free end of the bimetallic strips in a bimetallic thermometer with temperature is nearly

A

linear

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117
Q

Alphatron measures pressure __________ microns.

A

> 3

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118
Q

What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system ?

A

< 1

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119
Q

The unit step response of the transfer functionreaches its final steady state assymptotically after

A

a monotonic increase.

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120
Q

A process is initially at steady state with its output y=l for an input u=l. The input is suddenly changed to 2 at time t=0. The output response is y(t)=1+2t. The transfer function of the process is

A

1/s (1+2/s)

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121
Q

The term analogous to the electrical current in a thermal system is the

A

heat flow rate

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122
Q

Reset rate is the another term used for __________ time.

A

integral

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123
Q

Continuous measurement of moisture in paper is done by

A

high resistance Wheatstone’s bridge circuit.

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124
Q

Psychrometer determines the

A

humidity of gases

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125
Q

Which of the systems having the following transfer function is stable ?

A

1/s^2+2S+2

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126
Q

The calibration data of a thermocouple with its cold junction at 0°C are given below.

The hot junction of the thermocouple is placed in a bath at 80°C, while its cold junction is at 20°C. What is the emf of thermocouple ?

A

2.46 mv

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127
Q

A mercury barometer measures the __________ pressure.

A

atmospheric

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128
Q

Positioning controllers are used for

A

high loads

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129
Q

The amplitude ratio for the sinusoidal response of a __________ is 1.

A

transportation lag

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130
Q

The response of two tanks of same size and resistance in series is

A

critically damped

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131
Q

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

A

e^-τs

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132
Q

The amplitude ratio for the sinusoidal response of __________ is < 1.

A

first order system

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133
Q

Which of the following is a ‘contact’ pyrometer ?

A

resistance pyrometer

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134
Q

Which of the following is not a speed measuring instrument ?

A

Psychrometer

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135
Q

Measurement of sub-zero Celcius temperature in industry is done most commonly by

A

resistance thermometers

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136
Q

For the block diagram shown below :

The characteristic equation is1

A

τl S(τm S + 1) (τp S + 1) +Kc . Kp . Km (τl s + 1) e-τdS = 0

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137
Q

Use of I-control along with P-control facilitates

A

elimination of offset

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138
Q

Turbine flow meters are suitable for

A

both (b) and (c).

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139
Q

Liquid discharge from a tank or reservoir can not be measured by

A

orificemeters

140
Q

Which of the following is not a mechanical pressure sensing element ?

A

U-tube

141
Q

__________ are analysed using a polarograph.

A

Solids

142
Q

Which of the following judges the accuracy of an instrument ?

A

Static error

143
Q

On-off controllers are normally used for

A

low loads

144
Q

Magnetic flowmeters are generally not used for the velocity/flow measurement of hydrocarbons due to their

A

low electrical conductivity.

145
Q

Which of the following controllers has maximum offset ?

A

P-controller

146
Q

Pressure of 0.01 psi (absolute) can be measured by __________ gauge.

A

Mcloid

147
Q

High temperature of around 2000°C of incandescent gas mantles is measured by a/an

A

radiation pyrometer.

148
Q

The unit step response of the transfer function 1/(s2 + 2s + 3)

A

has a damped oscillatory characteristics.

149
Q

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

A
150
Q

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

A

5π/12

151
Q

Which of the following does not figure in the list of seven substances selected for international temperature scale ?

A

Zinc (B.P) and mercury (F.P

152
Q

A constant volume gas thermometer employing __________ is used to measure sub-zero (i.e., < 0° C) temperature.

A

helium

153
Q

pH meter has

A

two cells

154
Q

Routh test

A

cannot be used to test the stability of a control system containing transportation lag.

155
Q

The open loop transfer function of a process is . In the root locus diagram, the poles will be at

A

-2, -3

156
Q

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 :

A

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

157
Q

When a bare thermocouple is covered by a protective sheath, the response becomes

A

slower and non-oscillatory.

158
Q

What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple ?

A

13

159
Q

Helium gas constant volume thermometer is suitable for the measurement of a temperature of __________ °C.

A

< 0

160
Q

The transfer function of a second order system is

A
161
Q

Bode diagram are generated from output response of the system subjected to which of the following input?

A

Sinusoidal

162
Q

Which of the following thermocouples is the most suitable for measuring a temperature of about 1600°C in an oxidizing atmosphere ?

A

Platinum-platinum + rhodium

163
Q

Mercury thermometer can be used to measure the temperature upto __________ °C.

A

350

164
Q

The transfer function of a process is . If a step change is introduced into the system, then the response will be

A

under damped

165
Q

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

A

all ‘a’, ‘b’ & ‘c’.

166
Q

Which of the following is not a differential pressure flow meter ?

A

Rotameter

167
Q

Working principle of mercury in glass thermometer is based on volumetric expansion of mercury with increase in temperature. Which of the following undergoes minimum volumetric expansion for a given temperature change ?

A

Mercury

168
Q

Bourdon gauges are used for measuring pressure (kg/cm2 )

A

> 2 (gauge)

169
Q

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

A

light intensity

170
Q

A typical example of a physical system with under damped characteristic is a

A

spring loaded diaphragm valve.

171
Q

An aneroid barometer measures the __________ pressure.

A

absolute

172
Q

A bolometer is

A

both (a) & (b).

173
Q

Thermal wells are used in the temperature measurement to

A

guard against corrosive and oxidising action on thermocouple materials

174
Q

The offset introduced by proportional controller with gain Kcin response of first order system can be reduced by

A

introducing integral control.

175
Q

A system with a double pole at the origin is unstable since the corresponding term in the time domain

A

grows linearly with time.

176
Q

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

A

air

177
Q

In a second order under damped system, the

A

overshoot (which is a measure of how much the response exceeds the ultimate value) increase with the decrease of damping co-efficient e.

178
Q

In an exothermic chemical reactor, the manipulated variable is the flow rate of

A

coolant

179
Q

Very low pressure is expressed in microns(μ), which is equal to __________ mm of Hg coloumn (absolute) at 0°C.

A

0.001

180
Q

The inverse Laplace transform of the function is

A

1 - e^-t

181
Q

Thermal conductivity based continuous flue gas analyser makes use of varying thermal conductivity of the constituents of flue gases. Which of the following constituents of flue gases has the maximum thermal conductivity ?

A

CO2

182
Q

Emf generated in a thermocouple depends on the temperature

A

difference between hot and cold junctions.

183
Q

Working principle of mercury in glass thermometer is based on the __________ of mercury with increase in temperature.

A

volumetric expansion

184
Q

The Laplace transform of a sinusoidal function (eg; sin at) is represented by the curve

A
185
Q

Number of poles in a system with transfer function is

A

3

186
Q

Radiation thermometer can not measure the temperature

A

of liquid oxygen.

187
Q

Temperature measurement by optical pyrometer is done above __________ point, which is 1063°C.

A

gold

188
Q

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 ?

A

CO2

189
Q

Dilatometer is used to measure

A

contraction/expansion due to changes in temperature

190
Q

Mass spectrometer is used for the composition analysis of

A

isotopes

191
Q

A first order system with a time constant of 1 min is subjected to frequency response analysis. At an input frequency of 1 radian/min, the phase shift is

A

-45°

192
Q

__________ stability method uses open loop transfer function.

A

Nyquist

193
Q

A pyranometer is an instrument used for measuring the

A

global radiation.

194
Q

All the thermocouples used for temperature measurement use dissimilar metal

A

wires

195
Q

The transfer function of a first order system is

A

1 /Ts+1

196
Q

Composition of alloys can be determined by

A

polarograph

197
Q

Optical activity of a solution can be determined using a

A

polarimeter

198
Q

Stability of a control system containing a transportation lag can be best analysed by

A

frequency response methods

199
Q

Stabilising time for the controllers is the time required for the response to reach __________ percent of its ultimate value.

A

95

200
Q

Time constant is the

A

time taken by the controlled variable to reach 63.2% of its full change.

201
Q

Mercury manometer (U-tube type) exemplifies a __________ order system.

A

second

202
Q

Emf developed by a thermocouple while measuring a temperature of 400°C is 22 mV. The type of thermocouple used is

A

iron-constantan

203
Q

Bode stability method uses __________ loop transfer function.

A

open

204
Q

Working principle of bimetallic thermometers is difference in linear co-efficient of thermal expansion of two strips of different metals welded together. Which of the following has the maximum thermal co-efficient of linear expansion?

A

Brass

205
Q

Which of the following is not a second order instrument ?

A

Bare mercury in glass thermometer.

206
Q

Small furnace draught is accurately measured by an inclined tube manometer, in which the manometric liquid used most commonly is

A

paraffin

207
Q

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.

A

1

208
Q

A simple pitot tube measures the

A

static pressure

209
Q

For a feed back control system to be stable, the

A

poles of the closed loop transfer function should lie in the left half of the complex plane.

210
Q

A mercury thermometer can not be used to measure the temperature below the freezing point of mercury, which is __________ °C.

A

-38.9

211
Q

__________ controller has the maximum stabilising time.

A

PI

212
Q

Out of the following temperature measuring instruments, the measurement accuracy will be minimum for the

A

optical pyrometer.

213
Q

Stalagmometer is used for the measurement of

A

surface tension

214
Q

The deflection in diaphragm (which is used as pressure sensor in pneumatic and electronic instruments) is dependent on the metal thickness, its diameter (d) and shape & number of corrugations. Its deflection is proportional to

A

d^4

215
Q

Working principle of radiation pyrometer is based on the

A

stefan-Boltzman law

216
Q

Liquid levels in autocalves are measued by

A

differential float type manometer

217
Q

E.m.f. generated by thermocouples is of the order of

A

millivolts

218
Q

A pyrheliometer is an instrument used for measuring the

A

beam radiation.

219
Q

Flow rate through an orifice is __________ the pressure differential.

A

proportional to the square root of

220
Q

Thermistors are used in __________ devices.

A

both(b)&(c)

221
Q

__________ is the static characteristics of an instrument,

A

Drift

222
Q

Phase lag of the frequency response of a second order system to a sinusoidal forcing function

A

approaches 180° asymptotically

223
Q

Dead zone in an instrument must be less than __________ percent of the scale.

A

0.2

224
Q

Emission spectroscopy is used for

A

solids and metal analysis.

225
Q

Gas analysis is commonly done using the

A

thermal conductivity cell

226
Q

The open loop transfer function of a control system is KR/1+TS. This represents

A

a first order system.

227
Q

Thermal conductivity measurement is used for the determination of

A

CO2 percentage in the flue gas.

228
Q

Presence of a small amount of water in the organic systems can be determined by the __________ method.

A

dielectric constant end loss factor

229
Q

The transfer function of a pure dead time system with dead time τd is

A

e^-τss

230
Q

Thermal conductivity cell is the primary element of a/an __________ analyser.

A

carbon dioxide

231
Q

Zirconia probe is used for the measurement of

A

% O2 in flue gas.

232
Q

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

A

∞

233
Q

__________ type of element is normally not used in the bimetallic thermometers.

A

Bourdon tube

234
Q

Suppose that the gain, time constant and dead time of a process with the following transfer function:Gc(s) = 10 exp( - 0.1s)/(0.5s + 1) are known with a possible error of ± 20% of their values. The largest permissible gain Kc of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as

A

12, 0.6, 0.12

235
Q

Process degree of freedom indicates __________ number of controllers to be used.

A

the maximum

236
Q

Characteristic equation is the denominator of __________ loop transfer function.

A

closed

237
Q

Operating range of a temperature measuring instrument is 800 to 1600°C. It could be a/an __________ pyrometer.

A

photoelectric

238
Q

Polarograph is meant for the analysis of

A

solids

239
Q

Which of the following fluid flow measuring devices can measure the largest flow rate ?

A

Weir

240
Q

Flow rate of sludge is not measured by a/an

A

both(b)&(c)

241
Q

In a shell and tube heat exchanger, the inlet temperature of heating/cooling fluid is the __________ variable.

A

load

242
Q

Which of following error integral is considered as the best criterion in controller settings ?

A
243
Q

Polarisation of light forms the working principle of a

A

polarimeter

244
Q

A bimetallic thermometer as compared to industrial mercury in glass thermometer has almost the same

A

all a, b & c.

245
Q

Thermal wells used in temperature measurements should have

A

high transmissivity of radiation.

246
Q

Which of the following flow-metering instru-ments is an areameter ?

A

Rotameter

247
Q

Out of the following themocouple wire insulating material, the highest temperature rating is for

A

ceramic fibre

248
Q

Which is the most suitable instrument for measuring pressure below 3 microns ?

A

Ionisation gauge

249
Q

Routh stability method uses __________ loop transfer function.

A

closed

250
Q

Pyrometry refers to the measurement of temperature

A

which is of higher magnitude.

251
Q

Photoelectric pyrometers are suitable in the temperature range of __________ °C.

A

800-1600

252
Q

Non-metallic diaphragm used as pressure sensor in instruments is generally made of

A

synthetic rubber

253
Q

Response of a linear control system for a change in set point is called

A

servo problem

254
Q

Hot wire anemometer is used for the measurement of

A

flow rates of fluids.

255
Q

Which of the following thermocouples has the widest temperature measurement range ?

A

Platinum-platinum/rhodium

256
Q

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

A

air to open valve with the controller indirect acting.

257
Q

Bourdon tube is never made of

A

cast iron

258
Q

“An emf of the order of mV is generated when two solutions of different hydrogen ion concentration are separated by a thin glass wall”. This is the working principle of a

A

pH meter

259
Q

Pick out the symbol for “locally mounted instrument” in instrumentation diagram.

A

O

260
Q

Block diagram of a simple standard control system is shown below in the figure.
Which of the following statement about the above control system is wrong ?

A

Manipulated variable is represented by C.

261
Q

Water is flowing through a series of four tanks and getting heated as shown in figure. It is desired to design a cascade control scheme for controlling the temperature of water leaving the tank 4 as there is a disturbance in the temperature of a second stream entering the tank 2. Select the best place to take the secondary measurement for the second loop.

A

Tank 3

262
Q

The term analogous to voltage in a single tank system is the

A

level of liquid.

263
Q

In a shell and tube heat exchanger, the outlet temperature of heating/cooling fluid is the __________ variable.

A

controlled

264
Q

Mcleoid gauge is used to measure the

A

vacuum

265
Q

What is the Laplace transform of impulse input having magnitude ‘X’ ?

A

1

266
Q

Thermocouple is suitable for measuring

A

both high and low temperatures.

267
Q

Bimetal strips are not used in

A

thermocouples

268
Q

When the damping co-efficient (ξ) is unity, the system is

A

Critically damped.

269
Q

Nickel percentage in invar which is an iron-nickel alloy, and is used as a thermocouple material is

A

36

270
Q

Which is the symbol for “pneumatic control valve” ?

A
271
Q

Silver point temperature is __________ °C.

A

960.5

272
Q

A non-linear system will have __________ steady state values.

A

more than one

273
Q

Which of the following is not a variable area flow meter ?

A

Magnetic flow meter

274
Q

With increase in temperature, the electrical conductivity of the platinum used in the resistance thermometer

A

decreases

275
Q

Sub-zero temperature (< 0°C) can be measured by a constant volume gas thermometer employing

A

helium

276
Q

__________ is an example of distributed parameter system

A

Tubular reactor

277
Q

Which of the following is not classified as a thermo electric pyrometer ?

A

Optical pyrometer (disappearing filament type)

278
Q

Maximum differential pressure in liquid manometer is __________ psi.

A

30

279
Q

Phase margin is equal to

A

180° - phase lag

280
Q

In a feed-back control system G and H denote open loop and close loop transfer functions respectively. The output-input relationship is

A

H/1+G

281
Q

Flow rate measurement of hostile acids and alkalis can be most suitably done by a/an

A

magnetic flow meter

282
Q

Compositional analysis of flue gas coming out of a furnace in respect of O2 and CO2% can be continuously done by a/an

A

thermal conductivity cell

283
Q

Thermisters which have a very high temperature co-efficient of resistivity belong to the class of solid called

A

semi conductors

284
Q

The pressure sensing element of elastic type pressure gauge is never made in the form of a

A

strip

285
Q

Liquid flow rate in an open channel can not be measured by a/an

A

orifice meter

286
Q

The unit of ‘time constant’ of a system is the same as that of

A

time

287
Q

Which of the following filled system expansion thermometers has the lowest positive temperature measurement capability ?

A

Alcohol in glass thermometer.

288
Q

Liquid column manometers are used for measuring the pressure __________ kgf/cm2 .

A

< 3 (gage)

289
Q

Cascade control means

A

more than one feed-back loop.

290
Q

The level of a liquid under pressure can be determined using

A

differential pressure manometer

291
Q

Temperature measurement range of iron-constantan thermocouple is 0 to 870°C. It can be used to measure sub zero temperature, because at lower temperature

A

both (b) and (c).

292
Q

Which of the following is never used as an element of industrial resistance thermometer ?

A

Lead

293
Q

Which of the following shows maximum dip effect (indicating reverse direction of temperature change) ?

A

Mercury thermometer

294
Q

A stable system is the one

A

for which the output response is bounded for all bounded input.

295
Q

The Laplace transform of exp(at), where a > 0, is defined only for the Laplace parameter, s > a since

A

the Laplace transform of integral of exp(at) has finite values only for s > a.

296
Q

Meleoid gauge measures the __________ pressure.

A

sub-atmospheric

297
Q

Which of the following thermocouples is capable of measuring a temperature of -50°C?

A

Platinum - platinum + rhodium

298
Q

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).

A

w = sqrt 7/6, Kc = 46/3

299
Q

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.

A

630.74

300
Q

Change of angle of refraction with composition comprises the working principle of a

A

refractrometer

301
Q

Which of the following instruments is not used for measuring sub-zero (<0°) temperatures ?

A

Radiation pyrometer

302
Q

Which of the following is not suitable for measuring the temperature of a red hot object in the range of 800 - 1600°C ?

A

Thermocouples

303
Q

Find the Laplace transform of the following input function shown in figure.

A
304
Q

Flame photometry is used for the determination of compositional analysis of

A

alkali metals

305
Q

Reference points i.e., ice point and steam point in Reaumer temperature scale are respectively

A

0° & 80°

306
Q

Which of the following is not a composition measuring instrument ?

A

Hot wire anemometer

307
Q

Emf developed by a thermocouple while measuring a temperature of 800°C is about 31 mV. The type of thermocouple used is

A

chromel-alumel

308
Q

Which of the following thermocouples is incapable of measuring sub-zero (i.e., < 0°C) temperature ?

A

Platinum-platinum + rhodium

309
Q

Platinum resistance thermometer is the international standard for temperature measurement between

A

both (a) and (b)

310
Q

0n-off control which is a special case of proportional control, has a band width of about __________ percent.

A

0

311
Q

The thermal emf-temperature relationship of most thermocouples is

A

parabolic

312
Q

Which is the strongest paramagnetic gas?

A

O2

313
Q

In Bode plot, A.R. vs. w is plotted on a/an __________ graph paper.

A

log-lag

314
Q

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

A

1/sqrt2

315
Q

A control system has the following transfer function

The initial value of the corresponding time function is

A

1

316
Q

For measuring the temperature of a red hot furnace, which is the most suitable instrument ?

A

Optical pyrometer

317
Q

Continuous measurement of specific gravity of a liquid is done by

A

both (a) and (c)

318
Q

Stroboscope is used for the measurement of

A

rpm of a flywheel

319
Q

The root locus plot of the roots of the characteristics equation of a closed loop system having the open loop transfer function will have a definite num-ber of loci for variation of K from 0 to ∞. The number of loci is

A

3

320
Q

In second order underdamped system,

A

decay ratio = (overshoot)2

321
Q

Dome temperature of blast furnace stove is most accurately measured by a

A

platinum-platinum/rhodium ther-mocuple.

322
Q

Phase lag of the sinusoidal response of a first order system is

A

90°

323
Q

Continuous measurement of moisture content of paper in paper industry is done by measuring the

A

electrical resistance through the paper

324
Q

Thermal well made of __________ gives the fastest speed of response, while measuring temperature by thermocouples.

A

vycor (a glass)

325
Q

What is the Laplace transform of sin t ?

A

1/s^2+1

326
Q

Pick out the wrong statement.

A

Transfer lag decreases as the number of stages decreases.

327
Q

Working principle of mercury in glass thermometer is

A

volumetric expansion.

328
Q

The frequency at which maximum amplitude ratio is attained is called the __________ frequency.

A

resonant

329
Q

Which of the following can measure temperatures in the range of - 20 to 300°C ?

A

None of these.

330
Q

If response of a control system is to be free of offset and oscillation, the most suitable controller is

A

proportional integral-derivative (PID) controller.

331
Q

Conversion formula for converting amplitude ratio (AR) into decibels is

A

Decibel = 20 log10 (AR)

332
Q

A manometer measures the __________ pressure.

A

gauge

333
Q

Normal mercury thermometer can be used to measure a temperature of about 300°C. However, its maximum temperature measurement range can be increased upto about 500°C by

A

filling nitrogen under pressure in the stem.

334
Q

Minute depression of freezing point of a liquid solvent on addition of a solid solute can be best measured by a

A

Beckman thermometer

335
Q

For the time domain function f(t) = t, the Laplace transform of is given by

A

1/S3

336
Q

Temperature of __________ can not be measured by an optical or radiation pyrometer.

A

hot blast (air) from stoves

337
Q

Gain margin is equal to the

A

reciprocal of amplitude ratio

338
Q

A system with transfer function is of __________ order.

A

1st

339
Q

In Bode plot, Φ vs ω is plotted on a/an __________ graph paper.

A

log-log

340
Q

Temperature of molten pig iron (1450°C) and molten slag (1500°C) flowing out of a blast furnace is measured by a/an

A

either (b) or (c)

341
Q

For two non-interacting first order systems connected in series, the overall transfer function is the __________ of the individual transfer functions.

A

product

342
Q

Ordinary mercury in glass thermometer is used for measuring temperature upto 120°C. However, for measuring higher temperature upto __________ °C, thermometer is made by filling nitrogen under pressure above the mercury, which stops the evaporation of mercury and reduces the chance of broken thread of mercury.

A

550

343
Q

Mercury thermometer is commonly used for low temperature measruement. The freezing point and boiling point of mercury are respectively __________ °C.

A
  • 39 and 350
344
Q

Which of the following thermocouples has the least temperature measurement range?

A

Copper-constantan

345
Q

Composition of natural gas is determined by the

A

both (b) and (c)

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