UV-Vis and Mass Spectroscopy Quiz

What is the main purpose of UV-Vis spectroscopy?

• To measure the amount of light absorbed by a sample

• To measure the amount of light transmitted through a sample

• To measure the amount of light emitted by a sample

• To measure the amount of light reflected by a sample

Answer explanation

UV-Vis spectroscopy is used to measure the amount of light absorbed by a sample, making it the main purpose of this technique.

Which component of a UV-Vis spectrophotometer is responsible for selecting specific wavelengths of light for sample analysis?

• Interference filter

• Absorption filter

• Monochromator

• Cutoff filter

Answer explanation

The monochromator is responsible for selecting specific wavelengths of light for sample analysis in a UV-Vis spectrophotometer.

What is the relationship between absorbance (A) and transmittance (T) in UV-Vis spectroscopy?

• A = 1/T

• A = T

• A = log(1/T)

• A = log(T)

Answer explanation

Absorbance (A) in UV-Vis spectroscopy is related to transmittance (T) by the equation A = log(1/T), indicating a logarithmic relationship between the two.

What is the main strength of UV-Vis spectroscopy as an analytical technique?

• Limited applications

• High cost of operation

• Complex data analysis

• Non-destructive nature

Answer explanation

The main strength of UV-Vis spectroscopy is its non-destructive nature, allowing samples to be analyzed without altering or damaging them.

Which application of UV-Vis spectroscopy involves monitoring bacterial growth?

• Beverage analysis

• Pharmaceutical analysis

• DNA and RNA analysis

• Bacterial culture

Answer explanation

UV-Vis spectroscopy is used in monitoring bacterial growth through bacterial culture, making it the correct choice among the given options.

Which component of a UV-Vis spectrophotometer may cause measurement errors due to a small amount of light from a wide wavelength range still being transmitted?

• Interference from multiple absorbing species

• Light scattering

• Geometrical considerations

• Stray light

Answer explanation

Stray light in a UV-Vis spectrophotometer can cause measurement errors by allowing light from a wide wavelength range to still be transmitted, leading to inaccuracies.

In pharmaceutical analysis, how can UV-Vis spectroscopy be used to identify individual compounds in overlapping absorbance peaks?

• By processing spectra using mathematical derivatives

• By increasing the concentration of the compounds

• By changing the light source

• By using a different type of cuvette

Answer explanation

UV-Vis spectroscopy can be used to identify individual compounds in overlapping absorbance peaks by processing spectra using mathematical derivatives.

All electromagnetic waves travel at the speed of light.

• True

• False

When a molecule absorbs energy in the UV or Visible region

-------------------- transition takes place?

• Vibrational

• Rotational

• Electronic

• Vibrational-rotational

Which transition requires low energy?

• sigma to sigma *

• 
  pi to pi*

• 
  n to sigma*

• n to pi*