This set of Fermentation Technology Multiple Choice Questions & Answers (MCQs) focuses on “Instrumentation and Control – Dissolved Oxygen Monitoring”.
1. The details of steam-sterilized electrodes was given by ________
a) Lee and Tsao
b) Kell et al.
c) Schwan
d) Buhler and Ingold
View Answer
Explanation: Lee and Tsao in 1979 gave the details of steam sterilized oxygen electrodes. Those electrodes were useful for the measurement of oxygen concentration. It measures the partial pressure of dissolved oxygen.
2. The probe signal of O2 is determined by the equation ____________
a) P(O2) = C(O2) * TP
b) P(O2) = C(O2) * PT
c) P(O2) = C(O2) / PT
d) P(O2) = C(O2) + PT
View Answer
Explanation: The probe signal of O2 is determined by the equation: P(O2) = C(O2) * PT where P(O2) is the partial pressure of dissolved oxygen sensed by the probe, C(O2) is the volume or mole fraction of oxygen in the gas phase, and PT is the total pressure.
3. Which of the following acts as the anode in the galvanic electrode?
a) Silver
b) Magnesium
c) Lead
d) Platinum
View Answer
Explanation: Lead acts as the anode in the galvanic electrode whereas silver acts as the cathode. The galvanic electrode is used in the measurement of the partial pressure of the dissolved oxygen (DO) concentration.
4. Which of the following is used as an electrolyte in the galvanic electrode?
a) NaCl
b) KCl
c) SnCl2
d) MgCl2
View Answer
Explanation: Potassium Chloride is used as an electrode in a galvanic electrode. However, Potassium hydroxide or bicarbonate or acetate is an alternative to Potassium chloride.
5. Which of the following is not used in DO measurement?
a) Polarographic electrode
b) Tubing method
c) Tachometers
d) Galvanic electrode
View Answer
Explanation: The tachometer is used in the measurement of pressure. The tubing method, polarographic electrode, galvanic electrode, etc are used in the measurement of dissolved oxygen concentration.
6. Which of the following method is uses fluorescence for oxygen measurement?
a) Tubing method
b) Fluorometric method
c) Polarographic method
d) Galvanic method
View Answer
Explanation: The fluorometric method uses fluorescence phenomena for the measurement of dissolved oxygen. It has a fast response and is based on the fact that change in the partial pressure of oxygen quenches the fluorescence lifetime of a chromophore.
7. Which of the following is not the type of paramagnetic gas analyzers?
a) Magnetodynamic
b) Thermomagnetic
c) Magnetopneumatic
d) Load cells
View Answer
Explanation: The load cells are the cells used for determining the weight of the fermenter vessel. The paramagnetic gas analyzers are of three types: magnetodynamic, thermomagnetic, and magnetopneumatic.
8. Which of the following has a dumbbell shape?
a) Magnetodynamic
b) Thermomagnetic
c) Magnetopneumatic
d) Load cells
View Answer
Explanation: The magnetodynamic type is of the shape of a dumbbell. It is a type of gas analyzer which is used for the measurement of dissolved oxygen.
9. Which of the following is not used for monitoring the pH?
a) Glass electrode
b) Galvanic electrode
c) Silver electrode
d) Combined electrode
View Answer
Explanation: The galvanic electrode is used in the measurement of dissolved oxygen. Whereas, glass electrodes, silver electrodes, combined electrodes are used in the measurement of pH of a solution.
10. Which of the following makes contact with a solution whose pH is to be measured?
a) Ceramic plug
b) Electrolyte
c) Silver wire
d) Reference solution
View Answer
Explanation: The ceramic plug or bulb is the part of an electrode which makes the contact with the solution whose pH is to be measured. Electrolyte, Silver wire, Reference solution are the part of pH electrodes.
11. What is the value of Faraday’s constant?
a) 96500 J/mol
b) 96400 J/mol
c) 36300 J/mol
d) 36500 J/mol
View Answer
Explanation: The value of Faraday’s constant is 96500 J/mol. It was a constant named after famous scientist Michael Faraday. The Faraday constant equals 1 Faraday of charge per mole.
12. pH is the measurement of _________
a) concentration of H+
b) concentration of H–
c) concentration of OH+
d) concentration of OH–
View Answer
Explanation: The pH is the measurement of H+ ions in the solution. The pH scale was given by Sorenson. pH scale consists of numbers 1 to 14 with a pH of 1 being most acidic and 14 being most basic. pH 7 is a neutral solution.
13. Thermomagnetic is a ‘wind type’ analyzer.
a) True
b) False
View Answer
Explanation: Thermomagnetic is a wind type gas analyzer used for the measurement of dissolved oxygen concentration. It is the measure of magnetic susceptibility of the substance that is magnetized.
14. Nitric oxide exhibits the paramagnetic property.
a) True
b) False
View Answer
Explanation: Nitric oxide exhibits the paramagnetic property and has the ability to get attracted to the magnetic field. The electrons get weakly magnetized in presence of the magnetic field.
15. Which of the following is a ferromagnetic substance?
a) Cobalt
b) Nitrogen
c) Nitric oxide
d) Helium
View Answer
Explanation: Cobalt, Iron are examples of a ferromagnetic substance. The electrons aligned themselves in the direction of the magnetic field and are strongly magnetized. Here, Nitrogen is a diamagnetic material and Nitric oxide is a paramagnetic material.
Sanfoundry Global Education & Learning Series – Fermentation Technology.
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