Analytical Instrumentation Questions and Answers – H2S Analysers

This set of Analytical Instrumentation Multiple Choice Questions & Answers (MCQs) focuses on “H2S Analysers”.

1. Which of the following is not an advantage of electrochemical cells used for analysis of H2S?
a) Portable battery operated instrument
b) Pocket sized instrument
c) No pumps are needed
d) No interference from background gases
View Answer

Answer: d
Explanation: Electrochemical cells are affected by interference from background gases. Some of them are sulphur dioxide, carbon monoxide, nitric oxide and chlorine.

2. Which of the following methods are mainly used in combustible gas detection equipment?
a) Lead acetate tape staining method
b) Solid state sensor
c) Gold film sensor
d) Electrochemical cells
View Answer

Answer: b
Explanation: Solid state sensors are mainly used in combustible gas detection equipment. It is a semiconductor sensor.

3. Which of the following is not an advantage of solid state sensor used for analysis of H2S?
a) No sampling system
b) It can be used in conditions involving vibration
c) It can be used in corrosive atmosphere
d) No interference from background gases
View Answer

Answer: d
Explanation: Solid state sensors are affected by interference from background gases. Some of them are hydrogen, isopropanol and ethyl and methyl mercaptan.
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4. Which is the compound that forms the stain in Lead Acetate Tape Staining method used for the analysis of Hydrogen Sulphide and what is the colour of the stain?
a) Lead Sulphide, red colour
b) Lead Sulphide, brown colour
c) Hydrogen acetate, white colour
d) Hydrogen acetate, green colour
View Answer

Answer: b
Explanation: Hydrogen Sulphide reacts with Lead Acetate to form Lead Sulphide which is brown in colour. Hydrogen acetate in other words is acetic acid and is colourless.

5. Which of the following methods is not used for detection of hydrogen sulphide?
a) Lead acetate tape staining method
b) Solid state sensor
c) Chemiluminescence method
d) Electrochemical cells
View Answer

Answer: c
Explanation: Chemiluminescence method cannot be used for the detection of hydrogen sulphide. Others method that are used are using photometric analyser and using gold film sensor.

6. In solid state sensor, when heated to 150o to 300o which of the following occurs?
a) Resistance decreases with increase in H2S concentration
b) Resistance increases with H2S concentration
c) No change in resistance occurs
d) Sensor does not respond in this temperature range
View Answer

Answer: a
Explanation: In solid state sensor, when heated to 150o to 300o resistance decreases with increase in H2S concentration. The decrease in resistance is a logarithmic function of H2S concentration.

7. In the gold film sensor, the change in resistance is proportional to the concentration of H2S.
a) True
b) False
View Answer

Answer: a
Explanation: Gold film sensor works on the principle of absorption. The change in resistance is proportional to the concentration of H2S.
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8. Which of the following occurs in Electrochemical cells used for the detection of hydrogen sulphide?
a) Change in resistance
b) Redox reaction
c) Oxidation-reduction reaction
d) Change in colour
View Answer

Answer: c
Explanation: In Electrochemical cells, an oxidation-reduction reaction occurs in the presence of hydrogen sulphide. A current starts flowing and it is proportional to the concentration of hydrogen sulphide.

9. Which of the following is not a component of solid state sensor used for detection of hydrogen sulphide?
a) Heater
b) Thermistor
c) Semiconductor film
d) Photo detector
View Answer

Answer: d
Explanation: For measuring H2S, the sensor must be maintained at a particular temperature. This is done by using a heater. The temperature is monitored using a thermistor.
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10. The diagram of Electrochemical cell used for the detection of hydrogen sulphide is given below. Identify the unmarked component.
Find unmarked component in diagram of Electrochemical cell
a) Filter
b) Gas permeable membrane
c) Elastic layer
d) Electrolyte
View Answer

Answer: b
Explanation: The unmarked component is gas permeable membrane. Electrochemical cell is an electrochemical gas diffusion sensor.

Sanfoundry Global Education & Learning Series – Analytical Instrumentation.

To practice all areas of Analytical Instrumentation, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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