Colorimetry and Spectrometry Multiple Choice Questions and Answers

Colorimetry and Spectrometry Multiple Choice Questions and Answers


1. Beer’s law states that the intensity of light decreases with respect to ___________
a) Concentration
b) Distance
c) Composition
d) Volume
Answer: Concentration.

2. Laminar flow burner used in Flame photometers is also known as ____________
a) Turbulent burner
b) Premix burner
c) Total consumption burner
d) Nozzle mix burner
Answer: Premix burner.

3. Bolometer, a type of detector, is also known as ___________
a) Resistance temperature detector (RTD)
b) Thermistor
c) Thermocouple
d) Golay cell
Answer: Thermistor.

4. Lambert’s law states that the intensity of light decreases with respect to __________
a) Concentration
b) Distance
c) Composition
d) Volume
Answer: Distance.

5. In Michelson’s interferometer, the __________ of the detector output will depend upon the intensity of incoming radiation.
a) Velocity
b) Frequency
c) Amplitude
d) Phase
Answer: Amplitude.

6. In Flame emission photometers, the measurement of _____________ is used for qualitative analysis.
a) Colour
b) Intensity
c) Velocity
d) Frequency
Answer: Colour.

7. In Flame emission photometers, the measurement of _____________ is used for quantitative analysis.
a) Colour
b) Intensity
c) Velocity
d) Frequency
Answer: Intensity.

8. In Michelson’s interferometer, the frequency of the detector output can be determined by translating the _________ of movable mirror and the ___________ of monochromatic radiation.
a) Velocity, wavelength
b) Thickness, intensity
c) Length, velocity
d) Angle, intensity
Answer: Velocity, wavelength.

9. In the most widely used beam splitter, a thin film of ________ is sandwiched between two plates of low refractive index solid. Fill the blank with a suitable option.
a) Mylar
b) Silicon carbide
c) Ferrous oxide
d) Silver chloride
Answer: Mylar.

10. Beer Lambert’s law gives the relation between which of the following?
a) Reflected radiation and concentration
b) Scattered radiation and concentration
c) Energy absorption and concentration
d) Energy absorption and reflected radiation
Answer: Energy absorption and concentration.

11. The representation of Beer Lambert’s law is given as A = abc. If ‘b’ represents distance, ‘c’ represents concentration and ‘A’ represents absorption, what does ‘a’ represent?
a) Intensity
b) Transmittance
c) Absorptivity
d) Admittance
Answer: Absorptivity.

12. Which of the following is the wavenumber of UV and Visible radiation?
a) 1 x 10^6 to 1.3 x 10^4 m^-1
b) 1 x 10^6 to 1.3 x 10^4 m
c) 13 – 27 m^-1
d) 1 x 10^6 to 1.3 x 10^4 m^2
Answer: 1 x 10^6 to 1.3 x 10^4 m^-1

13. Spectroscopy deals with interaction of electromagnetic radiation with matter. What is the speed of this radiation in vacuum in m/s?
a) 6 x 10^8
b) 5 x 10^8
c) 7 x 10^8
d) 3 x 10^8
Answer: 3 x 10^8

14. Which of the following is not a limitation of Beer Lambert’s law, which gives the relation between absorption, thickness and concentration?
a) Concentration must be lower
b) Radiation must have higher bandwidth
c) Radiation source must be monochromatic
d) Does not consider factors other than thickness and concentration that affect absorbance
Answer: Radiation must have higher bandwidth.

15. Which of the following is not true about Absorption spectroscopy?
a) It involves transmission
b) Scattering is kept minimum
c) Reflection is kept maximum
d) Intensity of radiation leaving the substance is an indication of a concentration
Answer: Reflection is kept maximum.

16. Which of the following is not a property or parameter of electromagnetic radiation?
a) Wavelength
b) Voltage
c) Wave number
d) Amplitude
Answer: Voltage

17. What is the unit of absorbance which can be derived from Beer Lambert’s law?
a) L mol^-1 cm^-1
b) L gm^-1 cm^-1
c) Cm
d) No unit
Answer: No unit.

18. In which of the following ways, absorption is related to transmittance?
a) Absorption is the logarithm of transmittance
b) Absorption is the reciprocal of transmittance
c) Absorption is the negative logarithm of transmittance
d) Absorption is a multiple of transmittance
Answer: Absorption is the negative logarithm of transmittance.

19. What is the unit of molar absorptivity or absorptivity which is used to determine absorbance A in Beer Lambert’s formula?
a) L mol^-1 cm^-1
b) L gm^-1 cm^-1
c) Cm
d) No unit
Answer: L mol^-1 cm^-1.

20. Which of the following is the wavelength of microwave radiation?
a) 10 – 780nm
b) 0.78 – 30┬Ám
c) 0.6 – 10 m
d) 0.75 – 3.75 mm
Answer: 0.75 – 3.75 mm

21. Which type of Quantum Transition takes place in Ultra Violet and Visible spectroscopy?
a) Rotation of molecules
b) Nuclear
c) Bonding electrons
d) Spin of nuclei in a magnetic field
Answer: Bonding electrons

22. Which of the following is not a type of Spectroscopy?
a) Gamma ray
b) X ray
c) Nuclear magnetic resonance
d) Sound
Answer: Sound

23. Transmittance is given as T = P/Po. If Po is the power incident on the sample, what does P represent?
a) Radiant power transmitted by the sample
b) Radiant power absorbed by the sample
c) Sum of powers absorbed and scattered
d) Sum of powers transmitted and reflected
Answer: Radiant power transmitted by the sample.

24. Which of the following is false about the wavelengths of electromagnetic radiation?
a) Radiation with short wavelengths have high energies
b) Energy does not depend on wavelength
c) Radiation with long wavelengths have low energies
d) Energy depends on wavelength
Answer: Energy does not depend on wavelength

25. Which of the following is not an advantage of Laminar flow burner used in Flame photometry?
a) Noiseless
b) Stable flame for analysis
c) Efficient atomization of sample
d) Sample containing two or more solvents can be burned efficiently
Answer: Sample containing two or more solvents can be burned efficiently.

26. How is the wave number of electromagnetic radiation related to wavelength?
a) It is the reciprocal of wavelength
b) It is directly proportional to wavelength
c) It is not related to wavelength
d) It is equal to wavelength
Answer: It is the reciprocal of wavelength

27. Which of the following is not a detector used in Flame emission photometers?
a) Photronic cell
b) Photovoltaic cell
c) Photoemissive tube
d) Chromatogram
Answer: Chromatogram.

28. Which of the following is the principle of Flame emission photometers?
a) Radiation is absorbed by non-excited atoms in vapour state and are excited to higher states
b) Medium absorbs radiation and transmitted radiation is measured
c) Colour and wavelength of the flame is measured
d) Only wavelength of the flame is measured
Answer: Colour and wavelength of the flame is measured.

29. Which of the following is the advantage of prism monochromators?
a) Dispersion is non-overlapping
b) Dispersion occurs in non-linear manner
c) Dispersion is overlapping
d) Dispersion occurs in a linear manner
Answer: Dispersion is non-overlapping.

30. Which of the following is not an application of Flame emission photometers?
a) Analysis of biological fluids
b) Determination of sodium, potassium in soil
c) Determination of metals such as Mn, Cu
d) Analysis of complex mixtures
Answer: Analysis of complex mixtures.

31. Which of the following is the advantage of grating monochromators?
a) Dispersion is non-overlapping
b) Dispersion occurs in non-linear manner
c) Dispersion is overlapping
d) Dispersion occurs in a linear manner
Answer: Dispersion occurs in a linear manner.

32. Which of the following is not an advantage of a photovoltaic cell which is used as a detector in Flame emission photometers?
a) Portable
b) No external supply
c) Robust in construction
d) Does not show fatigue
Answer: Does not show fatigue.

33. In Atomic Absorption Spectroscopy, which of the following is the generally used radiation source?
a) Tungsten lamp
b) Xenon mercury arc lamp
c) Hydrogen or deuterium discharge lamp
d) Hollow cathode lamp
Answer: Hollow cathode lamp.

34. Which of the following is the principle of Atomic Absorption Spectroscopy?
a) Radiation is absorbed by non-excited atoms in vapour state and are excited to higher states
b) Medium absorbs radiation and transmitted radiation is measured
c) Colour is measured
d) Colour is simply observed
Answer: Radiation is absorbed by non-excited atoms in vapour state and are excited to higher states.

35. Which of the following is the function of the chopper in Atomic Absorption Spectroscopy?
a) To split the beam into two
b) To break the steady light into a pulsating light
c) To filter unwanted components
d) To reduce the sample into atomic state
Answer: To break the steady light into a pulsating light.

36. In Atomic Absorption Spectroscopy, with what material is the cathode in Hollow cathode lamp constructed?
a) Tungsten
b) Quartz
c) Element to be investigated
d) Aluminium
Answer: Element to be investigated.

37. How can the intensity of radiation be increased in Hollow cathode lamp?
a) Addition of non-conductive protective shield of mica
b) Addition of nitrogen to neon or argon in the lamp
c) Increasing the pressure of the filling gas
d) Changing the metal of the anode
Answer: Addition of non-conductive protective shield of mica.

38. Which of the following is the function of the Flame or Emission system in Atomic Absorption Spectroscopy?
a) To split the beam into two
b) To break the steady light into pulsating light
c) To filter unwanted components
d) To reduce the sample into atomic state
Answer: To reduce the sample into atomic state.

39. Which of the following is the function of the atomiser in the emission system of Atomic Absorption Spectroscopy?
a) To split the beam into two
b) To break the steady light into pulsating light
c) To break large mass of liquid into small drops
d) To reduce the sample into atomic state
Answer: To break large mass of liquid into small drops.

40. Which of the following is not a component of the emission system in Flame photometer?
a) Burner
b) Atomiser
c) Fuel gases and their regulation
d) Chopper
Answer: Chopper.

41. Which of the following is not a fuel used in flame photometry?
a) Acetylene
b) Propane
c) Hydrogen
d) Camphor oil
Answer: Camphor oil.

42. Which of the following options explains the process of ‘sputtering’ that occurs in Hollow Cathode Lamp?
a) Positive ions collide with cathode surface and metal atoms from cathode are ejected
b) Negative ions collide with cathode surface and metal atoms from anode are ejected
c) Positive ions collide with negative ions and metal atoms from anode are ejected
d) Positive ions collide with negative ions and photons are ejected
Answer: Positive ions collide with cathode surface and metal atoms from cathode are ejected.

43. Which of the following is not the requirement of a good flame in flame photometer?
a) Liquid sample must be evaporated to form solid residue
b) Solid residue must decompose to form atoms
c) Atoms must be produced such that they have the ability to get excited to higher states
d) Atoms must be produced such that they are in stable state
Answer: Atoms must be produced such that they are in stable state.

44. At what pressure should the gases in the sealed tube be maintained in the Hollow cathode lamp?
a) 1 to 5 torr
b) 20 to 30 torr
c) 40 to 50 torr
d) 50 to 55 torr
Answer: 1 to 5 torr.

45. Which of the following detectors is used to detect light intensities which are very weak?
a) Photomultiplier tube
b) Photovoltaic cell
c) Photoemissive tubes
d) Photo reflector
Answer: Photomultiplier tube.

46. Instead of glass filters, why gelatin filters could not be used for a long period while both are Absorption filters?
a) Gelatin tends to evaporate and hence they deteriorate
b) Gelatin is affected by humidity in the environment
c) They deteriorate due to absorption of heat leading to changes in gelatin
d) Gelation is affected by temperature in the environment
Answer: They deteriorate due to absorption of heat leading to changes in gelatin.

47. Which of the following detectors does not require a battery and is also known as barrier layer cell?
a) Photomultiplier tube
b) Photovoltaic cell
c) Photoemissive tubes
d) Photo reflector
Answer: Photovoltaic cell.

48. Which of the following could be used as the layer of dielectric in interference filters used in Absorption Spectroscopy?
a) Graphite
b) MgF2
c) Fe
d) AgNO3
Answer: MgF2.

49. How is Tungsten Halogen lamp differs from normal Tungsten filament lamp used in absorption spectroscopy?
a) It has a tungsten filament and is filled with inert gas
b) Iodine is added to normal filling gas
c) Iodine is coated on tungsten filament
d) Iodine is added to inert gas
Answer: Iodine is added to normal filling gas.

50. How does continuous wedge filter differ from normal interference filter used in absorption spectroscopy?
a) It permits continuous selection of different wavelength
b) It allows a narrow band of wavelengths to pass
c) It has two semi-transparent layers of silver
d) Space layer is made of a substance having low refractive index
Answer: It permits continuous selection of different wavelength.

51. How can stability of radiation be achieved in incandescent or discharge source used in Absorption Spectroscopy?
a) Using filters
b) Using monochromators
c) Using slits
d) By controlling the source voltage
Answer: By controlling the source voltage.

52. Which of the following statement is false about double beam absorption instruments?
a) It is similar to single beam instruments except two beams are present
b) Tungsten bulb is used as a source
c) Reference beam must have a higher intensity than sample beam
d) Both the beams after they pass through respective samples are compared
Answer: Reference beam must have a higher intensity than sample beam.

53. Which of the following is the purpose of balance indicator in double beam photometer or colorimeter?
a) Selects a particular wavelength
b) Splits the wavelength selected into two equal beams
c) Detects and indicates the amount of light falling on it
d) Indicates the difference between the output of two photometers
Answer: Indicates the difference between the output of two photometers.

54. Which of the following is not a reason for laser not being generally used as a source of radiation for UV, Visible Spectroscopy?
a) High cost
b) Limited range of wavelength
c) Less intensity
d) Complex to work with
Answer: Less intensity.

55. Which of the following statements is false about single beam absorption instruments?
a) Tungsten bulb is used as a source
b) Beam splitter is used to get parallel beam
c) Test tube is used as sample holder
d) Photovoltaic cell as detector
Answer: Beam splitter is used to get parallel beam.

56. Which of the following is not an application of colorimeter?
a) Paints
b) Inks
c) Cosmetics
d) Composition detection
Answer: Composition detection.

57. To tolerate high operating temperatures, which of the following has to be done in incandescent or tungsten filament lamps?
a) Alloys must be used
b) Nitrogen be used instead of inert gas
c) Envelope is fabricated with quartz
d) Envelope is fabricated with copper
Answer: Envelope is fabricated with quartz.

58. In photometers, the readings of the specimen are initially obtained in the form of which of the following parameters?
a) Transmittance
b) Absorption
c) Wavelengths
d) Volume
Answer: Transmittance.

59. Which of the following is the wave number of near infrared spectrometer?
a) 4000 – 200 cm^-1
b) 200 – 10 cm^-1
c) 12500 – 4000 cm^-1
d) 50 – 1000 cm^-1
Answer: 12500 – 4000 cm^-1.

60. Which of the following is a source used in spectroscopy?
a) LASER
b) Tube light
c) Sodium vapour lamp
d) Tungsten lamp
Answer: Tungsten lamp.

61. Which of the following is the purpose of the beam splitter in double beam photometer or colorimeter?
a) Splits beam into two equal intensity beams
b) Splits beam in such a way that sample beam has higher intensity
c) Splits beam in such a way that a reference beam has higher intensity
d) Merge two equal intensity beams into single beam
Answer: Splits beam into two equal intensity beams.

62. Which of the following is not a source used in Mid Infrared Spectrophotometer?
a) Nernst glower
b) High pressure mercury arc lamp
c) Globar
d) Nichrome wire
Answer: High pressure mercury arc lamp.

63. Which of the following is the principle of Golay cell which is used as a detector in IR spectroscopy?
a) Expansion of gas upon heating
b) Increase in resistance due to an increase in temperature and vice versa
c) Temperature difference gives rise to a potential difference in the material
d) Decrease in resistance due to an increase in temperature
Answer: Expansion of gas upon heating.

64. Which of the following options are correct in terms of wavelength for the different types of IR spectrometer?
a) Near IR: 0.8 – 2.5 mm
b) Mid IR: 0.8 – 2.5 mm
c) Far IR: 2.5 – 50 mm
d) Mid IR: 50 – 100 m
Answer: Near IR: 0.8 – 2.5 mm.

65. What is the composition of Globar rod which is used as a source in Mid IR spectroscopy?
a) Silicon carbide
b) Silver chloride
c) Silicon dioxide
d) Silver carbide
Answer: Silicon carbide.

66. Only pyroelectric transducer or pyroelectric crystals are used as detectors in Fourier Transform Infrared Spectrophotometer (FTIR). What is the main reason for other types of thermal detectors are not being used in FTIR spectrophotometer?
a) Less accuracy
b) Slower response
c) Less precision
d) Less sensitivity
Answer: Slower response.

67. Which of the following is not a composition of Nernst glower or Nernst filament?
a) Oxides of Zirconium
b) Oxides of Barium
c) Oxides of Yitrium
d) Oxides of Thorium
Answer: Oxides of Barium.

68. Which of the following is not used as pyroelectric material used in pyroelectric transducers in Infrared spectroscopy?
a) Triglycine Sulphate
b) Deutrated Triglycine Sulphate
c) Some Polymers
d) Tetraglycine sulphate
Answer: Tetraglycine sulphate.

69. Why is the computer necessary in Fourier Transform Spectrometer?
a) To display the detector output
b) To process the detector output
c) To determine the amplitude
d) To determine the frequency
Answer: To process the detector output.

70. In a solid sample treatment technique, the finely ground solid sample is mixed with mineral oil to make a thick paste which is then spread between IR transmitting windows. What is the name of this solid sample treatment technique?
a) Pressed pellet
b) Mull technique
c) Solid films
d) Solids run in solution
Answer: Mull technique.

71. Which of the following is not true about Fourier Transform Infrared (FTIR) spectrometer?
a) It is of non-dispersive type
b) It is useful where repetitive analysis is required
c) Size has been reduced over the years
d) Size has increased over the years
Answer: Size has increased over the years.

72. Which of the following is the reference that is generally used in FTIR interferometer?
a) Air
b) NaCl solution
c) Alcohol
d) Base solution
Answer: Air.

73. Which of the following is not the advantage of Fourier Transform Spectrometers?
a) Signal to noise ratio is high
b) Information could be obtained on all frequencies
c) Retrieval of data is possible
d) Easy to maintain
Answer: Easy to maintain.

74. Which of the following is not the function of the drive mechanism in Fourier Transform Infrared Spectrophotometer?
a) Movement of mirror to obtain a satisfactory interferogram
b) Acquire a good interferogram pattern
c) Allow 50% of the beam to pass
d) Keep the speed of the moving mirror constant
Answer: Allow 50% of the beam to pass.

75. Which of the following is not a technique for preparing solid samples in IR spectroscopy?
a) Solids run in solution
b) Mull technique
c) Solid films
d) Thin films
Answer: Thin films.

76. Which of the following has to be computed to determine transmittance and absorbance at various frequencies?
a) Ratio of signal and noise
b) Ratio of sample and reference spectra
c) Sample spectra
d) Reference spectra
Answer: Ratio of sample and reference spectra.


77. In Michelson Interferometer, if the reflected and transmitted beams are in phase at the beam splitter, then maximum intensity will reach the detector.
a) True
b) False
Answer: True.

78. Colorimeters are used in applications where great accuracy is required.
a) True
b) False
Answer: False.

79. Colorimeters are used to determine the concentration of solutions.
a) True
b) False
Answer: True.

80. Computer accepts analog signals directly.
a) True
b) False
Answer: False.

81. Atomic Absorption Spectroscopy is used for the analysis of metals.
a) True
b) False
Answer: True.

82. The function of pressure regulators in the emission system of flame photometer is to have a steady flame which is free from flickers.
a) True
b) False
Answer: True.

83. Velocity of electromagnetic radiation is more in a vacuum than in any medium.
a) True
b) False
Answer: True

84. Phototubes are more sensitive than photovoltaic cells.
a) True
b) False
Answer: True.

85. In Total consumption burner, only samples of particular droplet size will enter the burner.
a) True
b) False
Answer: False.

86. Atomic absorption spectroscopy is also called as Absorption Flame Photometry.
a) True
b) False
Answer: True.

87. Electromagnetic radiation can travel through a vacuum.
a) True
b) False
Answer: True

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