Analytical instruments MCQ Quiz Hub

1. 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?
Lead Sulphide, red colour
Lead Sulphide, brown colour
Hydrogen acetate, white colour
Hydrogen acetate, green colour

2. Which of the following methods is not used for detection of hydrogen sulphide?
Lead acetate tape staining method
Solid state sensor
Chemiluminescence method
Electrochemical cells

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

4. In the gold film sensor, the change in resistance is proportional to the concentration of H2S.
True
False
all of the above
None of the mentioned

5. Which of the following occurs in Electrochemical cells used for the detection of hydrogen sulphide?
Change in resistance
Redox reaction
Oxidation-reduction reaction
Change in colour

6. Which of the following is not a component of solid state sensor used for detection of hydrogen sulphide?
Heater
Thermistor
Semiconductor film
Photo detector

7. Which of the following is not a detector used in mid Infrared Spectrophotometer?
Thermopile
Thermistor
Pyroelectric cell
Golay cell

8. Why is the use of infrared analyzers limited when it comes to the analysis of inorganic compounds?
Slow response occurs
Less accurate results occur
Strong absorption of IR radiation by water
Small range

9. Which of the following is the chopping frequency used for industrial analyzers in the simple infrared analyser for gas analysis?
2-10 Hz
2-50 Hz
2-100 Hz
2-150 Hz

10. Which of the following is used as a source in the simple infrared analyzer for gas analysis?
Tungsten filament lamp
Nernst glower
Hot-wire spiral
Mercury arc lamp

11. Vibration excitation occurs only if the sample has hetero-atomic molecules.
True
False
all of the above
None of the mentioned

12. Which of the following is the relationship between the density of ideal gas and its molecular weight?
Directly proportional
Inversely proportional
Linear
No relation

13. Under which of the following conditions do all real gases behave as ideal gases to some extent?
Low temperature and low pressure
Low temperature and high pressure
High temperature and low pressure
Room temperature and normal pressure

14. Which of the following detectors are not used in analyzers based on gas density?
Hot wire
Platinum filament
Thermistor
Thermometer

15. When would the recorder indicate a zero base line in analyzers based on gas density?
When the detector on the sample side is cooler than that on the reference side
When the detector on the reference side is cooler than that on the sample side
When flow is unbalanced
When both the detectors are equally cooled

16. The use of thermistor eliminates the requirement for amplification.
True
False
all of the above
None of the mentioned

17. In analyzers based on gas density, the unbalance of the bridge is linearly proportional to which of the following?
Temperature of sample detector
Pressure at sample detector
Pressure difference between both the detectors
Gas-density difference between both the detectors

18. Which of the following bridges are used in analyzers based on gas density?
Wheatstone bridge
Kelvin’s bridge
Anderson’s bridge
Schering’s bridge

19. In analyzers based on gas density, if the sample carries a gas having a higher density than the detector which of the following occurs?
It will cause a net downward flow
It will cause a net upward flow
It splits into two beams
There will be no difference in flow

20. When hot-wires are used as detectors amplification is not required.
True
False
all of the above
None of the mentioned

21. Which of the following is the effective sample volume in analyzers based on gas density?
10 ml
20 ml
5 ml
50 ml

22. Gases emit radiation under which of the following conditions which can be used for determination of gases?
When mixed with other gases
When kept at suitable temperature
With sufficient electrical excitation and at suitable pressures
When exposed to radiation

23. Which of the following measuring technique is utilized for measuring nitrogen?
By using a method based on gas density
By using a method based on gas density
By using magnetic wind instruments
By using a photospectrometer where a gas sample is analysed and detected with a photocell

24. The characteristic emission of which colour, when discharge takes place in a low pressure chamber containing gas sample, will indicate the presence of nitrogen while using photospectrometer?
Purple
Blue
Pink
Green

25. Sample rates of nitrogen meter can be adjusted by doing which of the following?
By modifying the amplifier
With the help of the needle valve
By modifying the detector
By changing chopper frequency

26. Which of the following is the normal sampling rate used in nitrogen meters?
13 ml/min
33 ml/min
3 ml/min
43 ml/min

27. Nitrogen meters are calibrated for which of the following to measure nitrogen?
Mixture of nitrogen and air
Water saturated mixture of nitrogen and oxygen
Mixture of nitrogen and hydrogen
nitrogen

28. Why is nitrogen meters generally not calibrated for dry gases while measuring nitrogen?
It causes error
Range decreases
Reading tend to be non-linear
It cannot be measured

29. In which of the following ways can nitrogen be calibrated for dry gases?
By modifying the amplifier
By adjusting the needle valve
By modifying the detector
By changing chopper frequency

30. The voltage required for striking the discharge in the presence of nitrogen is 1500V.
True
False
all of the above
None of the mentioned

31. The light output from the discharge tube is interrupted by means of a rotating slotted disc.
True
False
all of the above
None of the mentioned

32. In West-Gaeke colourimetric procedure, the intensity of the red purple colour is measured photometically and it is proportional to the concentration of sulphur dioxide. What is the red purple coloured compound?
Sodium tetra chloromercurate
Dicholorosulphitomercurate complex
Ammonia molybdate
Paraosaniline sulphonic acid

33. The conductivitimetry method, involves bubbling sulphur dioxide through a solution containing sulphuric acid and which of the following?
Water
Hydrogen peroxide
Iodine
Formaldehyde

34. Which of the following are not the characteristics of conductivitimetry method used to measure sulphur dioxide?
Fast response
High sensitivity
Free from interference by other gases
Good accuracy

35. Which of the following are not the characteristics of colorimetry method used to monitor sulphur dioxide?
It is simple
It has high sensitivity
It has good specificity
It is affected by interference from H2SO4, SO3, NH3, etc

36. Which of the following is not true about using gas chromatography for measuring pollutants in the air?
Pollutants react rapidly in the column
Pollutants may not be detected by the detectors
Special column and support materials are required
Pollutants may elude rapidly from the column

37. The ability of sulphur dioxide to reduce iodine is used in which of the following methods?
Colorimetry
Conductivitimetry
Coulometry
Gas chromatography

38. Which of the following materials are used as electrodes in the coulometric method for the measurement of sulphur dioxide?
Gold
Silver
Platinum
Nickel

39. Which of the following is the detection limit of the coulometric method used for measurement of sulphur dioxide?
0.1 ppm
1 ppm
2 ppm
0.01 ppm

40. Sensitivity to total sulphur by Flame-photometric detector is which of the following levels?
0.1 ppm
1 ppm
2 ppm
0.01 ppm

41. Which of the following methods are not used for the measurement of sulphur dioxide?
Colorimetric method
Correlation spectroscopy
Paramagnetic analyzers
Flame-photometry

42. Which of the following is the wavelength of the radiation generated when an air stream containing sulphur dioxide is burned in a hydrogen-rich flame?
243 nm
394 nm
467 nm
516 nm

43. In conductivitimetric method, the concentration of sulphur dioxide is proportional to which of the following parameters of the saw-tooth waveform?
Average voltage
Peak voltage
Slope
RMS voltage

44. In the conductivitimetric method, to measure the conductivity of the cell, 5V ___________ is applied across the electrodes.
DC
AC
Pulsating DC
DC or AC

45. The response of coulometric method is instantaneous.
True
False
all of the above
None of the mentioned

46. In Saltzman method, which of the following are formed when air containing NO2 is passed in an absorbing solution consisting of the sulphanilic acid and diamine dissolved in the acetic acid medium?
Blue colour dye complex
Green colour dye complex
Pink colour dye complex
Orange colour dye complex

47. NO can be analysed by converting it into NO2 and passing it through potassium permanganate. Which of the following is the main disadvantage of this method?
Less accuracy
Dye formed is unstable
Dye formed is colourless
Quantity of dye is low

48. In Jacob-Hochheiser method, NO2 is passed through a dilute solution of sodium hydroxide forming the nitrite ion. The nitrite ion is reacted with sulphanilamide and ethylene diamine in which of the following to form the highly coloured azo dye?
Sulphuric acid
Hydrochloric acid
Nitric acid
Phosphoric acid

49. Which of the following methods results in the formation of yellow coloured compound?
Griess-Saltzman method
Phenoldisul phonoic acid method
Chemiluminescence method
West-Gaeke method

50. Which of the following is the most common application of Chemiluminescence method used for the analysis of Nitrogen oxides?
In medical applications
In automotive exhaust gases
In manufacturing processes
In chemical industries