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Lesson: UV–Vis Spectroscopy Methods

Worksheet • 9 Questions

Q1:

Flame atomic absorption measures absorption of radiation of analytes in which phase?

  • AGas phase
  • BPlasma phase
  • CSolid phase
  • DAqueous phase
  • ELiquid (neat) phase

Q2:

Which one of the following cannot be detected by fluorescence or phosphorescence spectroscopy?

  • AUncomplexed metal ions
  • BVitamins
  • CPharmaceuticals
  • DEnvironmental pollutants

Q3:

How does turbidimetry differ from nephelometry?

  • ATurbidimetry measures the decrease in transmittance of incident radiation; nephelometry measures the intensity of scattered radiation.
  • BThe terms are synonymous; there is no difference.
  • CNephelometry measures the decrease in transmittance of incident radiation; turbidimetry measures the intensity of scattered radiation.
  • DTurbidimetry measures the total metal ion, or inorganic, content; nephelometry measures total organic content.
  • ENephelometry measures the total metal ion, or inorganic, content; turbidimetry measures total organic content.

Q4:

In size exclusion chromatography, what happens to the larger particles?

  • AThey elute first, before smaller particles.
  • BThey bind permanently to the stationary phase.
  • CThey are broken down into smaller particles.
  • DThey remain on the column longer than smaller particles.
  • EThey become oxidized as they move through the column.

Q5:

Why is fluorescence spectroscopy often carried out in a liquid nitrogen environment?

  • APhosphorescence is more likely to occur at low temperatures in a viscous medium.
  • BThe source radiation can overheat and destory the analyte.
  • CPhosphorescent molecules tend to also have explosive properties.
  • DThe detector requires lower temperatures for operation.
  • EThe monochromator slows down the radiation before it hits the sample.

Q6:

Why are flourescence and phosphorescence spectra measured at a 90 degree angle to the source?

  • ATo ensure that incident (source) photons are not observed.
  • BTo make the overall instrument smaller.
  • CBecause the sample cell is darkened on two adjacent sides.
  • DBecause the process of fluorescence and phosphorescence are too intense to observe directly.
  • EBecause the monochromator directs the light at a 90 degree angle.

Q7:

Which of the following statements about UV-Visible spectrophotometers is not true?

  • AA simultaneous UV-Vis instrument contains mirrors and a monochromator in order to allow simultaneous detection at various wavelengths.
  • BDeuterium or tungsten lamps are commonly used as light sources.
  • CSingle-beam and double-beam instruments contain a filter for selecting one wavelength at a time.
  • DA diode array detector eliminates the need for a monochromator.

Q8:

Turbidimetry and nephelometry are analytical methods based on which of the following?

  • ALight scattering
  • BParamagnetism
  • CPhoton emission
  • DNuclear repulsion
  • EPhoton absorption

Q9:

Basic UV-Visible spectroscopy is designed to analyze samples in what phase?

  • ASolution (or liquid) phase
  • BSolid (or suspension) phase
  • CPlasma phase
  • DGas phase
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