Questions and answers for exam Preparation

MCQs

Total Questions : 147 | Page 1 of 15 pages

Question 1. UV-Vis spectroscopy of organic compounds is usually concerned with which electronic transition(s)?

σ → σ*
n → σ*
n → π* and π → π*
none of these

Discuss Question

Answer: Option C. -> n → π* and π → π*
Answer: (c).n → π* and π → π*

Question 2. A simple harmonic oscillator may absorb energy

at anytime.
when the frequencies match exactly
when the amplitudes are the same.
at no time.

Discuss Question

Answer: Option B. -> when the frequencies match exactly
Answer: (b).when the frequencies match exactly

Question 3. Which of the following components of a monochromator is the dispersing element?

The collimating lens
The entrance slit
The diffraction grating
None of these

Discuss Question

Answer: Option C. -> The diffraction grating
Answer: (c).The diffraction grating

Question 4. Vibrational spectroscopy is

a large mass on a weak spring
a flashlight through a prism and shake it
a class of spectroscopic techniques which analyzes molecular motions
an Infrared spectroscopy

Discuss Question

Answer: Option C. -> a class of spectroscopic techniques which analyzes molecular motions
Answer: (c).a class of spectroscopic techniques which analyzes molecular motions

Question 5. Why are rotational transitions of little use to a spectroscopist?

Because the energy required to induce a rotational transition is so small that it cannot be measured
Because rotational transitions are extremely rare
Because, in liquids and solids, spectral lines corresponding to rotational transitions are broadened as the result of molecular collisions and other interactions
All of the above

Discuss Question

Answer: Option C. -> Because, in liquids and solids, spectral lines corresponding to rotational transitions are broadened as the result of molecular collisions and other interactions
Answer: (c).Because, in liquids and solids, spectral lines corresponding to rotational transitions are broadened as the result of molecular collisions and other interactions

Question 6. All hydrogen atoms

have the same resonance frequency
resonate at different frequencies depending on their environment.
are attached to carbon
resonate at about the same frequency as carbon

Discuss Question

Answer: Option B. -> resonate at different frequencies depending on their environment.
Answer: (b).resonate at different frequencies depending on their environment.

Question 7. What is the name given to the relaxation process due to an interaction between an excited nucleus and the magnetic fields caused by nuclei in molecules moving around in the sample?

Spin - lattice relaxation
Spin - spin relaxation
Spin - spin - spin relaxation
None of these

Discuss Question

Answer: Option A. -> Spin - lattice relaxation
Answer: (a).Spin - lattice relaxation

Question 8. Cytochrome C has an isoelectric pH of

8.5
10.05
7.5
11.05

Discuss Question

Answer: Option B. -> 10.05
Answer: (b).10.05

Question 9. Why is it important to use a deuterated solvent?

NMR uses least of this solvent
So the spectrometer can lock onto the sample to prevent the spectrum from drifting during aquisition
Expensive solvents work best with NMR
They dissolve polymer the fastest

Discuss Question

Answer: Option B. -> So the spectrometer can lock onto the sample to prevent the spectrum from drifting during aquisition
Answer: (b).So the spectrometer can lock onto the sample to prevent the spectrum from drifting during aquisition

Question 10. What does the Michelson interferometer do?

Split a polychromatic beam of radiation into its component wavelengths
Selectively filter certain wavelengths from a beam of I.R. radiation
Modulate the I.R. signal at a lower frequency, so that it can be observed by a detector
none of the above

Discuss Question

Answer: Option C. -> Modulate the I.R. signal at a lower frequency, so that it can be observed by a detector
Answer: (c).Modulate the I.R. signal at a lower frequency, so that it can be observed by a detector