Process Control and Instrumentation

121. Measurement of sub-zero Celsius temperature in industry is done most commonly by

1. Thermocouples
2. Resistance thermometers
3. Gas thermometers
4. Bi-metallic thermometers

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

1. Zero
2. First
3. Second
4. Third

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

1. 100
2. 250
3. 350
4. 750

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

1. - 39 and 350
2. - 51 and 439
3. - 79 and 395
4. - 10 and 425

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

1. Beckman thermometer
2. Dilatometer
3. Mercury thermometer
4. Bimetallic thermometer

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126. Nichol's chart deals with

1. A.R. vs. phase lag of first order
2. A.R. vs. phase lag of second order
3. Closed loop values vs. open loop values
4. Frequency response values of controllers

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

1. 12
2. 36
3. 54
4. 68

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

1. 0-100
2. < 0
3. < 100
4. < 50

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

1. Teflon
2. Synthetic rubber
3. Bakelite
4. Thick paper

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130. 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

1. Filling nitrogen under pressure in the stem
2. Increasing the diameter of the tube
3. Using steel tube in place of glass tube
4. Accounting for the tube expansion

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