Final Exam Practice Questions

Question 1

A scientist analyzes a sample of ground water to determine which heavy metals have contaminated
the source. This is an example of a:
a. qualitative analysis
b. quantitative analysis

Answer 1

qualitative analysis

Question 2

Identify the metric prefix that corresponds to the factor 10-6

Answer 2

micrograms

Question 3

What does the TC marking on glassware mean?

Answer 3

to contain

Question 4

Would TC be more likely to be found on a volumetric pipet or a volumetric flask?

Answer 4

vol flask

Question 5

Which of the procedures, if either, is more accurate (i.e. less error) when making a 1/50 dilution of a
solution?
a. Transfer 20 mL with a pipet into a 1-L volumetric flask.
b. Transfer 1 mL with a pipet into a 50-mL volumetric flask.
c. Both procedures have the same accuracy.

Answer 5

a. Transfer 20 mL with a pipet into a 1-L volumetric flask.

Question 6

Systematic Error, Random Error, or Blunder?

A student removes the cuvette from the UV/Vis while collecting data for a kinetics experiment

Answer 6

blunder

Question 7

Systematic Error, Random Error, or Blunder?
A student sets an Eppendorf pipet at 49 uL instead of 50 uL and uses it that way throughout the
experiment.

Answer 7

systematic

Question 8

Aliquots from a blood sample are sent to three separate laboratories for analysis using the same
method. Does this exercise primarily check the accuracy of the analysis or the precision of the
analysis?

Answer 8

precision

Question 9

What is the relationship between the standard deviation and the accuracy of a procedure?

a. the smaller the standard deviation, the greater the accuracy
b. the larger the standard deviation, the greater the accuracy
c. there is no relationship between standard deviation and accuracy

Answer 9

c. there is no relationship between standard deviation and accuracy

Question 10

The copper content of 18-carat gold was measured by two methods for six different samples collected 
from a jewelry production plant.
Which test would you use to determine if the results obtained by the two methods agree within 
experimental error?
a. 𝐹 test only
b. Grubbs test
c. paired 𝑡 test
d. a Q test

Answer 10

c. paired 𝑡 test

Question 11

The iodide (I−) content of a commercial mineral water was measured by two methods that produced
very different results. Method A detected an iodide content of 0.23 milligrams of I- per liter (mg/L) and
method B found 0.005 mg/L.. When Mn2+ was added to the water, the I- content found by method A
increased each time that more Mn2+was added, but the results from method B were unchanged.
Which term describes what is occurring in these measurements?
a. interference
b. masking
c. quantitative transfer
d. decanting

Answer 11

a. interference

Question 12

The iodide (I−) content of a commercial mineral water was measured by two methods that produced
very different results. Method A detected an iodide content of 0.23 milligrams of I- per liter (mg/L) and
method B found 0.005 mg/L.. When Mn2+ was added to the water, the I- content found by method A
increased each time that more Mn2+was added, but the results from method B were unchanged.
Which method is more reliable?
a. Method A
b. Method B
c. The methods are equally reliable.

Answer 12

b. Method B

Question 13

A student measured the sulfite content (wt%) of a solid sample six times
The chemical supplier certifies the sulfite content of the sample to be 51.64 wt%.
Which case describes how an instructor would determine if the two results differ at a given
confidence level?
a. Case 1: Replicate measurements of a sample made by a single technique are compared
with an accepted value.
b. Case 2: Either compare replicate measurements of one sample made by two analytic
techniques, or compare samples created from two synthesis techniques measured by
one analytic technique.
c. Case 3: Multiple samples are measured by two different techniques and the results are
compared.

Answer 13

a. Case 1: Replicate measurements of a sample made by a single technique are compared
with an accepted value.

Question 14

Your company validated an analytical method in your R&D facility last month. You now need to transfer the
analytical method to a production plant in Taiwan so that they will be able to release product. In order to ensure that their lab will be able to successfully execute the method (and because your quality systems require it) you will need to document a method transfer. They have never used a similar method, and sending them samples will take too long because of customs delays.
What kind of method transfer should you do?
a. Comparative Testing
b. Co-Validation
c. Revalidation
d. Transfer Waiver

Answer 14

c. Revalidation

Question 15

A scientist analyzes a sample of ground water to determine how much lead is present. This is an
example of a _________.
a. qualitative analysis
b. quantitative analysis

Answer 15

b. quantitative analysis

Question 16

What does the TD marking on glassware mean?

Answer 16

to deliver

Question 17

When preparing a buret for use in lab, the buret must always be cleaned thoroughly. Prior to being
filled with solution, the buret is rinsed one last time.
What is the buret rinsed with, and why?
a. Deionized water should be used to ensure that all of the soap has been removed from the buret.
b. The titrant should be used to ensure that when added to the buret the titrant will not be
diluted with water

Answer 17

b. The titrant should be used to ensure that when added to the buret the titrant will not be
diluted with water

Question 18

Systematic Error, Random Error, or Blunder?
The volume of water in a 100 mL graduated cylinder is recorded by several students in a group.
Their recorded volumes are all similar but vary by 0.01 mL.

Answer 18

random error

Question 19

Systematic Error, Random Error, or Blunder?

A student spills a volumetric flask while filling it.

Answer 19

blunder

Question 20

A known amount of analyte is added to an aliquot of the sample and analyzed with the sample.
Does this exercise primarily check the accuracy of the analysis or the precision of the analysis?

Answer 20

accuracy

Question 21

What is the relationship between the standard deviation and the precision of a procedure?

a. the smaller the standard deviation, the greater the precision
b. the larger the standard deviation, the greater the precision
c. there is no relationship between standard deviation and precision

Answer 21

a. the smaller the standard deviation, the greater the precision

Question 22

A researcher wants to compare the precision of two different assays for the determination of a tumor
marker in blood serum.
The researcher finds that one method gives a measured concentration of 20.45 ± 0.06 ng/mL for 10
replicate measurements of the tumor marker.
The second method gives a measured tumor marker concentration of 21.62 ± 0.13 ng/mL for 10
replicate measurements of the same serum sample.
Which test should the researcher use to determine if the precision of the two methods is within
experimental error at a specific confidence interval?
a. 𝐹 test
b. Grubbs test
c. paired 𝑡 test
d. 𝑡 test

Answer 22

a. 𝐹 test

Question 23

The aluminum content of a glass frit was measured by two methods that produced very different
results. Method A detected an aluminum content of 7.52 weight % and method B found 12.11 weight %.
When Method A was modified such that the glass frit sample solution had potassium cyanide added
(known to complex zinc, which may also be present in the sample) – let’s call this Method C, it detected
an aluminum content of 7.54 weight %.
Which term describes what the role of potassium cyanide in Method C?
a. interference
b. masking
c. quantitative transfer
d. decanting

Answer 23

b. masking

Question 24

he aluminum content of a glass frit was measured by two methods that produced very different
results. Method A detected an aluminum content of 7.52 weight % and method B found 12.11 weight %.
When Method A was modified such that the glass frit sample solution had potassium cyanide added
(known to complex zinc, which may also be present in the sample) – let’s call this Method C, it detected
an aluminum content of 7.54 weight %.
What would you say about these methods’ reliability?
a. Method A is most reliable.
b. Method B is most reliable.
c. Method C is most reliable.
d. Methods B and C are equally reliable.

Answer 24

d. Methods B and C are equally reliable

Question 25

The ratio of carbon-14 to carbon-12 in living systems is important in radiocarbon dating. Researchers
measured the carbon-14 to carbon-12 ratio for several different samples via two techniques.
Which case describes how an instructor would determine if the two results differ at a given confidence level?
a. Case 1: Replicate measurements of a sample made by a single technique are compared
with an accepted value.
b. Case 2: Either compare replicate measurements of one sample made by two analytic
techniques, or compare samples created from two synthesis techniques measured by
one analytic technique.
c. Case 3: Multiple samples are measured by two different techniques and the results
are compared.

Answer 25

Case 3: Multiple samples are measured by two different techniques and the results
are compared.

Question 26

Your company is planning the method validation for a product that has been under development. As the
manufacturing site has been identified and they have a very well equipped and staffed Quality Control lab
on site, you know that a method transfer can allow their QC lab to do product release upon commercial production. After agreement with the QC lab management, you write up your validation protocol such that the R&D lab will execute most of the validation, and the QC lab will take part in the Reproducibility
experiment as well as executing forced degradation testing.
What kind of method transfer is described above?
a. Comparative Testing
b. Co-Validation
c. Revalidation
d. Transfer Waiver

Answer 26

b. Co-Validation

Question 27

Which does not result in deviations from linearity in a Beer’s law plot of absorbance versus
concentration?
a) light losses at the cell interface
b) a wide bandwidth relative to the width of the absorption band
c) stray radiation
d) equilibrium between different forms of the analyte
e) all are sources of nonlinearity

Answer 27

a) light losses at the cell interface

Question 28

When a molecule absorbs an infrared photon, which of the molecular transitions is observed?
electronic
vibrational
rotational
nuclear spin

Answer 28

vibrational

Question 29

In comparing fluorescence spectroscopy to UV‑Vis absorption spectroscopy, which of the
statements is true?
A) Fluorescence measurements are more precise and less noisy because only the intensity of the emitted light is measured.
B) Fluorescence measurements do not suffer deviations from linearity like absorbance measurements do.
C) Fluorescence measurements have better detection limits because at low concentrations a low intensity emission signal is being measured against a low
intensity background signal.
D) Fluorescence instruments are less expensive than absorption measurements.

Answer 29

Fluorescence measurements have better detection limits because at low concentrations a low intensity emission signal is being measured against a low
intensity background signal.

Question 30

Classify the phrases based on whether they describe fluorescence or phosphorescence.
______ S1 to S0
______ lower energy
______ shorter wavelength

Answer 30

F
P
F

Question 31

If I am developing a LC/MS method for polar molecules and want to maximize production of the
molecular ion (that is minimize fragmentation), what type of ionization would I use?
______ Electrospray Ionization
______ Electrospray Ionization with Collision Induced Dissociation
______ Electron Impact Ionization
______ Matrix Assisted Laser Desorption/Ionization (MALDI)
______ Direct Analysis in Real Time (DART)

Answer 31

Electrospray Ionization

Question 32

f I would like to use a mass spectrometry with my chromatography technique and I’d like a
relatively inexpensive mass spectrometer with unit resolution, I’d likely chose which mass
spectrometer?
______ Time of Flight (TOF)
______ Triple Quadrupole (QqQ)
______ Transmission Quadrupole – collision cell - Time of Flight (Q-TOF)
______ Transmission Quadrupole
______ Orbitrap

Answer 32

Transmission Quadrupole

Question 33

If I have decreased signal for the neutral alkali metal that I am trying to measure by atomic
spectroscopy due to its low ionization potential, what kind of interference is it?
______ Spectral Interference
______ Physical Interference
______ Chemical Interference
______ Ionization Interference

Answer 33

Ionization Interference

Question 34

If I wanted a light source that gives a narrow bandwidth of light without the need of filters,
which of the following would be the best choice?
______ A blackbody source like a globar
______ An arc source like a deuterium lamp
______ A line source like a mercury vapor lamp
______ A laser

Answer 34

A laser

Question 35

A laser works by light amplification through stimulated emission. The amplification occurs in the optical cavity created by what objects?

Answer 35

mirrors

Question 36

Atomic spectroscopy must provide background correction to distinguish analyte signal from
absorption, emission, and optical scattering of the sample matrix, the flame, red-hot graphite
furnace, or plasma. Which of the following is the name of the technique whereby a strong
magnetic field, applied parallel to the light path through a furnace, is pulsed on and off to create
alternating periods of signal due sample and background and signal due to the background
alone?
______ subtract adjacent pixels of CID display
______ beam chopping
______ deuterium lamp
______ Zeeman effect

Answer 36

Zeeman effect

Question 37

If you want to do quantitative atomic spectroscopy of many analytes at the lowest possible
detection limits, what technique should you choose?
______ ICP-MS
______ Graphite Furnace AA
______ X-Ray Fluorescence or Laser Induced Breakdown Spectroscopy
______ ICP-Optical Emission
______ Atomic Fluorescence
______ Flame AA
______ Laser Ablation – ICP

Answer 37

ICP-MS

Question 38

If you want to do qualitative atomic spectroscopy of a solid sample with many analytes at % levels
most economically, what technique should you choose?
______ ICP-MS
______ Graphite Furnace AA
______ X-Ray Fluorescence or Laser Induced Breakdown Spectroscopy
______ ICP-Optical Emission
______ Atomic Fluorescence
______ Flame AA
______ Laser Ablation – ICP

Answer 38

X-Ray Fluorescence or Laser Induced Breakdown Spectroscopy

Question 39

Which conditions can result in deviations from Beer’s law when the pathlength is constant?
_____ the absorbing species undergoes dissociation or association
_____ the sample is homogeneous
_____ stray light reaching the detector
_____ the use of polychromatic radiation
_____ solute concentrations less than 0.01 M

Answer 39

the absorbing species undergoes dissociation or association
stray light reaching the detector
the use of polychromatic radiation

Question 40

When a molecule absorbs an ultraviolet photon, which of the molecular transitions is observed? 
(Check the best answer.)
\_\_\_\_\_ electronic
\_\_\_\_\_ vibrational
\_\_\_\_\_ rotational
\_\_\_\_\_ nuclear spin

Answer 40

electronic

Question 41

Classify the terms based on whether they describe a radiative process or a nonradiative process.
(Label each line R or NR as appropriate.)
_____ phosphorescence
_____ internal conversion
_____ vibrational relaxation
_____ fluorescence

Answer 41

R
NR
NR
R

Question 42

Classify the phrases based on whether they describe fluorescence or phosphorescence. 
(Label each line F or P as appropriate.)
\_\_\_\_\_\_ T1 to S0
\_\_\_\_\_\_ higher energy
\_\_\_\_\_\_ longer wavelength

Answer 42

P
F
P

Question 43

If I am developing a GC/MS method and want to get maximum information about the structure (that
is, create many fragments), what type of ionization would I use?
______ Electrospray Ionization
______ Chemical Ionization
______ Electron Impact Ionization
______ Matrix Assisted Laser Desorption/Ionization (MALDI)
______ Direct Analysis in Real Time (DART)

Answer 43

Electron Impact Ionization

Question 44

If I am developing an electrospray LC/MS method and want to maximize production of the
molecular ion but also get fragmentation with high resolution of the fragment ions, what type of
mass spectrometer would I use?
______ Time of Flight
______ Triple Quadrupole (QqQ)
______ Transmission Quadrupole – collision cell - Time of Flight (Q-TOF)
______ Transmission Quadrupole
______ Orbitrap

Answer 44

Transmission Quadrupole – collision cell - Time of Flight (Q-TOF)

Question 45

If I have decreased signal in my atomic spectroscopy experiment due to the formation of sulfate or
phosphate salts of my analyte, what kind of interference is it?
______ Spectral Interference
______ Physical Interference
______ Chemical Interference
______ Ionization Interference

Answer 45

Chemical Interference

Question 46

If I wanted a light source that gives a broad spectrum of light in the infrared region, which of the following
would be the best choice?
______ A blackbody source like a globar
______ An arc source like a deuterium lamp
______ A line source like a mercury vapor lamp
______ A laser

Answer 46

A blackbody source like a globar

Question 47

Describe how an electron multiplier works.

Answer 47

Each electron striking the cathode releases multiple electrons through secondary electron emission.
These are accelerated to successive dynodes producing a multiplication effect before being read as
current at an anode.

Question 48

What does a diode laser have that a light emitting diode does not? That is, why is a diode laser a
laser and an LED not a laser?

Answer 48

An optical cavity, formed by polished sides acting as mirrors

Question 49

Atomic spectroscopy must provide background correction to distinguish analyte signal from
absorption, emission, and optical scattering of the sample matrix, the flame, red-hot graphite
furnace, or plasma. Which of the following is the name of the technique whereby blocking material
is rotated in front of the lamp to create alternating periods of signal due to the lamp and the flame
and signal due solely to the flame?
______ subtract adjacent pixels of CID display
______ beam chopping
______ deuterium lamp
______ Zeeman effect

Answer 49

beam chopping

Question 50

If you want to do quantitative atomic spectroscopy of a few analytes at ppm to ppb levels most
economically, what technique should you choose?
______ ICP-MS
______ Graphite Furnace AA
______ X-Ray Fluorescence or Laser Induced Breakdown Spectroscopy
______ ICP-Optical Emission
______ Atomic Fluorescence
______ Flame AA
______ Laser Ablation – ICP

Answer 50

Flame AA

Question 51

If you want to do qualitative atomic spectroscopy of many analytes in a solid sample at low ppb
detection limits, what technique should you choose?
______ ICP-MS
______ Graphite Furnace AA
______ X-Ray Fluorescence or Laser Induced Breakdown Spectroscopy
______ ICP-Optical Emission
______ Atomic Fluorescence
______ Flame AA
______ Laser Ablation – ICP

Answer 51

Laser Ablation – ICP

Question 52

ELISA (enzyme linked immunosorbent assay) is a common application of fluorescence used for its
ability to detect faint biochemical signals.
How does ELISA detect the analytes of interest?
_____ Different amounts of a fluorescent standard are added to the ELISA assay and a
calibration curve is made to estimate how strong the signal is.
_____ A fluorescent signal is released as the analytes bind to the antibodies on the polymeric
support of the assay.
_____ An enzyme, attached to an antibody bound molecule of analyte, catalyzes multiple
cycles of a reaction that generates a fluorescent product.
_____ Antibodies that bind specifically to the analyte of interest fluoresce once bound to the
analyte, creating a quantifiable signal to record.

Answer 52

An enzyme, attached to an antibody bound molecule of analyte, catalyzes multiple
cycles of a reaction that generates a fluorescent product.

Question 53

Is longitudinal diffusion of the solute a more serious problem in gas or in liquid chromatography?

Answer 53

More serious in GC due to easier diffusion

Question 54

Given the description, name the source of band broadening:
___produced by variable paths around support particles
___due to diffusion along the column length

Answer 54

Multiple Paths (or Tortuosity or Eddy Diffusion)
Longitudinal Diffusion

Question 55

For an open tubular column in gas chromatography, which term(s) in the van Deemter equation
does(do) not affect the plate height? (Check the best answer.)
_____ equilibration time and linear velocity
_____ linear velocity and multiple paths
_____ multiple paths and longitudinal diffusion
_____ longitudinal diffusion
_____ linear velocity
____ multiple paths

Answer 55

multiple paths

Question 56

Which of the following is a very poor choice as a starting point for method development?
(Check the worst idea.)
_____ I’d like to separate a group of proteins (20 kDa – 50 kDa) that have differing amounts of charged peptides, so I’ll try ion exchange chromatography with a wide pore stationary phase
____ I’d like to separate a hydrophobic drug (~200 Da) from its degradation products (similar structures as the drug and similar molecular weight), and both the drug and its degradation products are only soluble in organic solvents, so I’ll try reversed-phase HPLC with a C18 column
_____ I’d like to separate some low molecular weight sugars that have poor retention by reversed-phase HPLC, so I’ll try hydrophilic interaction chromatography HILIC.

Answer 56

I’d like to separate a hydrophobic drug (~200 Da) from its degradation products (similar structures as the drug and similar molecular weight), and both the drug and its degradation products are only soluble in organic solvents, so I’ll try reversed-phase HPLC with a C18 column

Question 57

Which of the following stationary phases are not used in the specified type of chromatography?
(Check the best answer.)
_____ C18 stationary phase for reversed-phase chromatography
___ Polar Embedded stationary phase for normal phase chromatography
_____ Porous Graphitic Carbon for reversed-phase chromatographic separation of positional
isomers

Answer 57

Polar Embedded stationary phase for normal phase chromatography

Question 58

Which of the following statements is true? (Check the best answer.)
_____ There are two maximum temperature limits given for GC columns. The lower one is the temperature at which bleed starts and the higher one is the temperature at which the phase no longer acts as a liquid.
____ There are two maximum temperature limits given for GC columns. The lower one is the isothermal temperature limit at which the column provides acceptable thermal stability and the higher one is the programmed temperature limit to which the column should only be exposed for a few minutes at a time.
_____ There is only one maximum temperature limit ever given for GC columns and it indicates the maximum temperature at which the column provides acceptable thermal stability.

Answer 58

There are two maximum temperature limits given for GC columns. The lower one is the isothermal temperature limit at which the column provides acceptable thermal stability and the higher one is the programmed temperature limit to which the column should only be exposed for a few minutes at a time.

Question 59

Which of the following describes the general elution problem in HPLC?
(Check the best answer.)
____ For a complex mixture, isocratic conditions can often be found to produce adequate separation of early-eluting peaks or late-eluting peaks, but not both. This problem drives us to use gradient elution.
_____ For a complex mixture, gradient conditions can often be found to produce adequate separation of early-eluting peaks or late-eluting peaks, but not both. This problem drives us to use isocratic elution.
_____ For a complex mixture, isocratic conditions can often be found to produce adequate separation of early-eluting peaks or late-eluting peaks, but not both. This problem drives us to use temperature programming.

Answer 59

For a complex mixture, isocratic conditions can often be found to produce adequate separation
of early-eluting peaks or late-eluting peaks, but not both. This problem drives us to use gradient
elution.

Question 60

Which of the following statements is false?
(Check the best answer.)
____ When analyzing “dirty” samples by HPLC, one should use a guard column to provide a little bit extra separating power.
_____ For separation of basic compounds at pH 8-12 ethylene-bridged silica or polymeric supports such as polystyrene can be used.
_____ The pores of an HPLC stationary phase must be sufficiently wide to allow solvent and solute molecules free access.

Answer 60

When analyzing “dirty” samples by HPLC, one should use a guard column to provide a little bit extra separating power.

Question 61

Which of the following statements is false?
(Check the best answer.)
____ N2 gives better resolution (smaller plate height) than H2 or He in GC at high flow rate because its higher mass drives analytes into the stationary phase.
_____ Helium is the most common carrier gas as it is compatible with most detectors and is not an explosion hazard.
_____ H2 can be run much faster than its optimal velocity with little penalty in resolution.

Answer 61

N2 gives better resolution (smaller plate height) than H2 or He in GC at high flow rate because its higher mass drives analytes into the stationary phase.