Forensics HW Sets
Which of the following methods are not widely used in the analysis of explosives?
Atomic absorption spectroscopy
Which substance has the highest ignition temperature?
Benzene
The wavelength range of visible light is approximately between 400 to 800 nm, in order to maximize the hiding power of a white pigment, its particle size should be
Between 200 to 400 nm
Which of the following statements with regard to ionization in an ion mobility spectrometry is true?
Molecules in air form clusters ions, mainly H(H2O)n+, in the positive-ion mode.
Tempera paints are made from
Egg yolks
A 12-gauge shotgun has a barrel of smaller diameter than a 16-gauge shotgun.
False.
The combustion continuum can be classified based on forensic application as fire, firearms and bombs. Which of them typically use oxygen as the oxidant in the combustion reaction?
Fire.
Infrared spectrophotometry of paint chips can be categorized as
Definitive identification
What kind of polymer is it with the following linkage?
Linear
In the following figure, which depicts the bias?
a. (the line from mean to mean between the two peaks)
Polymeric solids have characteristics that lie between the extremes of an ordered crystal and an amorphous solid possessing little organized structure.
True
QA is an all- encompassing, "cradle-to-grave" system that controls data generation.
True
The uncertainty of the Type A contributing factors can be captured and described by a standard deviation.
True
Under bright-field illumination (transmittance) microscope, an analyst can often determine the cross section of a fiber by its appearance from above by the shading.
True
The OH functionality of cellulose provides a chemical handle that is exploited for the generation of contiguous cellulose fibers. Which of the following fibers is not regenerated cellulose?
Nylon.
Which of the following drugs is often seized in liquid form, usually a greenish-colored solution with an overwhelming smell?
Phencyclidine
Raman interactions are dependent on the existence of
polarizable bonds
The necessary condition for lasing is
population inversion.
The following picture depicts that synthetic fibers of polymer is made by
wet spinning
Calculate the oxygen balance of HMX (the molecular mass of HMX, C4H8N8O8, and oxygen is 296.156 and 32.0, respectively).
-21.6%
Which of the following ruling that held evidence produced by scientific analysis is admissible as long as the techniques are accepted as valid by the relevant scientific community?
. The Frye Rule
Analytical quality control samples almost always accompany a sample run, and the collection (sample to be tested and quality control samples) is usually referred to as ______.
. a batch
Quinine (C20H24N2O2) is a dibasic molecule with pKas of 5.1 and 9.7. It is encountered as a diluent (cutting agent) for heroin. To successfully extract quinine from an aqueous solution, what pH should be used?
11.7
A 3.7 × 10−4 M solution of compound X has an absorbance of 0.5342 when measured at 740 nm. Assuming a pathlength of 1 cm, calculate compound X's molar absorptivity.
1443 M−1 cm−1
IR absorption bands that correlate to C=O stretching of polyesters, alkyds, acrylics and urethanes is
1650-1730 cm-1.
A transmittance of 0.3847 is measured for a 0.00023 M solution. Assuming a pathlength of 1 cm, calculate the molar absorptivity of the solute.
1803 M−1 cm−1
For a compound microscope, if the ocular is 10× and the objective lens is 40×, the virtual image appears
400 times larger than the sample
For a typical forensic microscope, the best wavelength in the following list that can be used for the examination of the smallest visible samples is
470 nm blue light
Which of the following light bents the least (is refracted to a smallest degree) when passing through an optical lens?
700 nm red light
The writing characteristics of a person may be altered by whether:
All of the above
What differs between firing a gun and a crude pipe bomb made of galvanized steel pipe and gunpowder is that burning of the gunpowder in a crude pipe bomb is not exploited to do PV work.
False
When a headspace method is used to determine blood alcohol concentration, the difference between the relative volatility of ethanol and water is exploited.
False
Tandem mass spectrometers are those that combine multiple mass filters in
. Either of above (space and time)
The following figure illustrates spots developed on a TLC. Please calculate Rf3
. 0.27
A .40 caliber pistol is loaded with a cartridge containing 3.2 grains of propellant which is rated at 3000 J/g. The barrel, which is carbon steel, has a heat capacity of 0.12 kcal/kg°C. Assume the barrel weighs 13.3 oz and 28% of the chemical energy is lost to the barrel as heat, estimate how much hotter the barrel gets after one shot. (1 g = 15.43 grains; 1 oz = 28.35 g; 1 kcal = 4.184 kJ)
. 0.9 °C
The following data about naproxen and codeine is obtained from the Clarke's Handbook. Naproxen: pKa = 4.2; log P = 3.2. Solubility of naproxen: insoluble in water, soluble 1 in 25 in ethanol, 1 in 15 in chloroform, and 1 in 40 in ether. Codeine: pKa = 8.2; log P = 0.6 . The HCl salt is soluble 1 in 20 in water, 1 in 180 in ethanol, and 1 in 800 in chloroform. The appropriate pH for a liquid-liquid extraction (LLE) scheme using water and chloroform to separate a sample containing naproxen sodium (an analgesic) and codeine as the hydrochloride salt is
. 10.2
During the quantitative analysis of cocaine using gas chromatography with external calibration, the following data was collected. When a sample was analyzed, the peak area was 71003. Please calculate the cocaine concentration in the sample.
. 167.5
Calculate the minimum grating length to successfully resolve 616.50 nm from 616.59 nm for first-order diffraction. The available diffraction grating is 103 grooves per cm.
. 6.85 cm
Suppose you have an acidic drug with a pKa of 5.0 that is in solution held at physiological pH. What is the %ionization of the drug?
. 99.6
Which of the following analytical method is not suited for paper analysis?
. All of above is suited for paper analysis
A microanalytical balance is purchased by a forensic laboratory. The analyst in charge is asked to develop an SOP and control chart to use as the basis of estimating uncertainty. The working range of the balance is 0.1 mg to 10 g. Based on the control chart, current calibration report, and manufacturer's literature, the analyst identifies three key contributing factors to the uncertainty: drift of the balance reading over time: 0.0002 g, rectangular distribution; repeatability, 0.0009 g normally distributed and obtained from a control chart; and readability in the last displayed decimal of 0.0001 g. What would be the expanded uncertainty with coverage factors of k=2?
0.0018 g
An autopipet arrives at the lab certified to deliver 200 L 2.0 L ( 1%). The analyst immediately validates this performance by repeatedly pipetting what the device records as 200 L aliquots into dried, tared containers on a calibrated analytical balance. By recording the water temperature and using a chart that relates density to temperature, the analyst converts the weight of water, in milligrams, to a volume delivered by the pipet. Please calculate the %RSD.
0.28
A forensic chemist prepares a standard of caffeine in chloroform for use in a quantitative assay. The caffeine is purchased from a reputable supply house and arrives with a certificate stating that it is 99.5% pure or better. The analyst needs to make a stock solution at a concentration near 1 mg/mL. To do so, he obtains a Type A 50.00 mL volumetric flask (+/- 0.05 mL) and uses a microbalance to accurately weight out 49.6 mg. The balance uncertainty is listed as +/- 0.0003 g near the 50 mg range. The analyst quantitatively transfers the powder to the flask and carefully dilutes the solution to volume. Report the concentration of the solution in mg/mL and the propagated uncertainty associated with it. Be sure to use the proper significant figures.
0.992 ± 0.006 mg/mL
A forensic chemist used the hypergeometric function in Excel, calculated the probability of drawing four playing cards from a shuffled deck and getting all aces, and reported as a percentage as a "1 in X" odds. Which result is correct?
1 in 270,725
Papaverine (MM=339.385) is a basic drug, S0 = 1.7x10-3 grams/100mL water; pKa = 6.36. Calculate the solubility at pH 4.8 in both M and g/100 mL.
1.9 ×10-3 M, 0.063 g/100mL
Agents of the Drug Enforcement Administration seize 5000 1-kg "bricks" containing a light tan powder that is suspected to contain heroin. Historically, such seizures are all pure heroin. Outwardly, all the packages appear similar. Use the ENFSI spreadsheet to select the number of samples that need to be collected and tested for the DEA to be 90% confident that at least 90% of the packages contain heroin if no negative is expected to be found in the subset sample.
22
By how many kilojoules per mole is the energy of CO2 increased when it absorbs infrared radiation with a wavenumber of 2 300 cm-1 (h = Planck's constant = 6.626 x 10-34 J-s; Avogadro number is 6.022 × 1023)?
28 kJ/mol
The following shows an example of uncertainty ellipses around the chromaticity coordinates obtained from fibers treated with a single dye. Which fiber has the deepest color?
4 (closest to the origin)
Typical wood samples contain approximately ___ cellulose.
40%
Using the Springhall Roberts rules to predict the products of an explosion of ethylene glycol dinitrate (EGDN, C2H4N2O6, molecular mass 152.1) and assuming ΔH° of EDGN is -227 kJ/mol, the relative explosive power (REP) of EGDN is subsequently calculated to be (the molar volume of a gas is 22.4 L)
5.1 kJL/g2
A solid phase extraction is illustrated as follows. Which analyte has the greatest relative affinity for the mobile phase?
A (the one that elutes out first)
When a gun is fired, the burning of the propellant is exploited to do PV work. Which of the following is a consequence of PV work other than energy loss?
A bullet is propelled out of a gun barrel.
Which is NOT true of the flame atomic absorbance spectroscopy of iron?
A detector measures the amount of light generated by the flame and not absorbed by iron
Which of the following fiber has negligible or undetectable birefringence?
Acetate
Most explosives can be recovered from debris for future study by being rinsed with:
Acetone.
Which is NOT part of the composition of paint?
Adhesive
The following paint binder is best categorized as
Alkyd.
Which of the following compound can be found in the primers of modern firearms?
All of above
Quality control does not include
All of above are included
Which of the following statements about traceability is correct?
All of above statements are correct.
IR spectra obtained by ATR are not directly comparable with transmission or reflection spectra because
All of above.
Questioned documents include:
All of the above
Which of the following sample preparation methods can be used in fire debris analysis?
All of them
Which of the following acids is the strongest on the basis of their pKa values: Phenylbutazone pKa = 4.40; Ascorbic acid pKa = 4.10; Arsenous acid (H3AsO3) pKa = 9.29.
Ascorbic acid
Which of the following light undergoes specular reflectance?
B (the one coming straight up)
Which is NOT a high explosive?
Black powder
Which of the following polyethylene may be used in food containers, shampoo bottles, and the like?
Right one
The FID is sensitive to compounds that contain ______ bonds, and the more of these bonds, the stronger is the response
C-H
A common classification system characterizes ignitable liquids based on their boiling point ranges and number of _____ molecules as light, medium, and heavy petroleum distillates.
Carbon
BF3 is an initiator for
Cationic polymerization.
Which of the following materials is not categorized as natural fiber?
Cellaphone
Amylose and amylopectin are referred to as vegetable fibers. Cellulose is used in plants as structural support in the form of microfibrils. Glycogen serves as a form of energy storage in animals and fungi. They are all glucose polymers. Which of them is composed of -1,4' linkages?
Cellulose
In drug analysis, the forensic frame work is
Classification-identification-individualization
In the following CIELAB color space as shown, the lightness of the two colors A and B is the same and a = b, then
Color A and B have the same saturation and different hue
The top-down model allows for the determination of several uncertainty contributors using one tool, which is usually a(n)
Control chart
The following monosaccharide is
D-glucose
Which of the following color test uses Co2+ as the reactive specie?
Dilli-Koppanyi
Which of the following drug was used in psychotherapy?
Ecstasy
______ has published a validated Excel workbook available online that contains an application of the hypergeometric distribution to sampling problems associated with large seizures of illicit drugs.
ENFSI
Which of the following drug is a depressant?
Ethanol
Which of the following analytical techniques is most widely used in classifying the binders used in paints?
FTIR spectroscopy
In quantitative analytical chemistry, the sensitivity is expressed as the limit of detection (LOD).
False
Defects that are reproduced by a photocopier onto a copied document may originate from defects in all of the following photocopier parts EXCEPT:
Feed tray
In a large population of measurements, the relative frequency of occurrence of measurement versus error of measurement is usually plotted and a curve is obtained. The shape of the curve is usually
Gaussian
For UV spectroscopy, the sample cell is made of
Fused silica
Which of the following separation technique uses a capillary tube coated with a material in which the analytes partition on the basis of their relative polarities and boiling points?
GC
Which of the following analytical method can be categorized as definitive identification
GC-MS
Which of the following ruling that stressed the need to weigh the relevancy of the data to the question at hand?
General Electric v. Joiner
Which of the following material remains dark in any orientation when it is placed between crossed polarizers of a polarized light microscopy (PLM)?
Glass
Which of the following controlled substance is in Schedule I?
Heroin
Which is a chemical used to synthesize the explosive TATP?
Hydrogen peroxide
Gas chromatography remains a workhorse inlet of forensic chemistry, be it for
Identification of accelerants
A red nylon fiber with a circular cross section is identified at the crime scene. A suspect wearing a red nylon windbreaker is arrested. Nylon fibers from the windbreaker (often labeled K for "known") are subjected to the same tests as was the fiber in question (Q) from the scene, with similar results. This is an example of ______ evidence
Inclusive
The following dye is best categorized as
Indigoid. (2 benzenes and 2 5-C rings)
In the analysis of explosives, which of the following methods are used to analyze anions?
Ion chromatography
In atomic spectroscopy, which of the following statements is NOT true for ionization interference?
Ionization interference occurs when a component of the sample prevents ionization of the sample
Which of the following question is not forensic question?
Is the defendant guilty of poisoning his son?
______ occurs for inductively coupled plasma-mass spectroscopy when the interfering species has the same mass-to-charge ratio as the analyte ion.
Isobaric interference
Which of the following is commonly used as the solvent in an ink formulation?
Isophorone
Which of the following statements about CMY color system is NOT true?
It is used in computer monitors and televisions.
Which of the following is NOT true for X-ray fluorescence?
K and K X-rays originate when L shell electrons transition to the K shell.
The Environmental Protection Agency has published a method (EPA 8330 and updates) that uses ______ to identify and quantify 14 nitroaromatic explosives including TNT, RDX, and degradation products.
LC/UV
Which of the following statements about paint analysis by microscopy is NOT true?
Microscopy can be used to observe the color layer sequence of paint chips, although individualized cannot be achieved in any circumstances.
If the exhibit is one tiny paint chip, the ideal analysis would be
Microspectrophotometry
The Hollywood staple of exploding gas tanks in cars is
More fiction than fact
Chitin is the tough material found in the exoskeletons of insects and arthropods. The monomer is
N-acetyl-D-glucosamine
The following shows an IMS spectra of 100 ng of (a) RDX, (b) NG, and (c) PETN using methylene chloride as doping agent. Which of the following statement is false?
NG is detected as Cl−
Double-base smokeless power contain
Nitroglycerin and nitrocellulose
Which property of noise does signal averaging exploit to improve the signal-to-noise ratio?
Noise is random
Which is NOT true of the plasma atomic spectroscopy?
One turn of a radio frequency induction coil wrapped around the upper opening of the quartz apparatus.
During a quantitation using UV/VIS spectrophotometry, the absorbance should be
Optimum between 0.4 and 0.9
Which chemical reaction is associated with a fire?
Oxidation
Which of the following drug is a narcotic?
Oxycodone
Which is often used as the explosive core in a detonating cord?
PETN
Which of the following statements about the collection of paint evidence involved in hit-and-run incidents is NOT true?
Paint chips ¼ inch square are insufficient for laboratory examination
The following dye is best categorized as
Phthalocyanine (the really complicated one)
In atomic spectroscopy, which of the following atomizing source produces the highest temperature?
Plasma
In atomic spectroscopy, which of the following atomizing sources does not require any lamps in the spectrometer?
Plasma
Which of the following atomic spectroscopic technique has the best linear range?
Plasma emission
The polymer with the following monomer and repeating unit is
Poly(methyl methacrylate) Plexiglas (3 C's and 2 O's)
The polymer with the following monomer and repeating unit is
Poly(vinyl chloride) (2 C's and 1 Cl)
The following polymer is best categorized as
Polyurethanes.
A case examination reveals the following fibers on a piece of evidence. Which one is the most likely relative evidentiary importance?
Purple polyester
Which of the following statements about pyrolysis GC-MS in forensic analysis of paints is true?
Pyrolysis GC-MS can be used to classify binders used in pains which have similar IR absorption spectra.
In which of the following techniques, glass can be used as the sample container when the sample is being analyzed?
Raman spectroscopy
In the CMY color system, equal amount of M and Y will produce
Red
Which mode of SPE employs a nonpolar terminal R group such as C18, which is chemically bonded to the silica backbone, and polar solvents?
Reversed phase
The Griess test uses
Sulfanilamide and N-(1-naphthyl)ethylenediamine in acidic solution
A plot to blow up ten international plane flights leaving Britain for the United States with a "liquid explosive" apparently involved plans to smuggle ____ onto the planes. This plot has prompted authorities to prohibit airline passengers from carrying liquids and gels onto planes.
TATP
Which of the following explosives can be analyzed based on the detection of H2O2 residuals in the explosive?
TATP
Which of the following controlled substance is in Schedule III?
Testosterone
Which of the following drug is used as a human-performance drug?
Testosterone
The following are FTIR spectra obtained with a sheathed bicomponent fiber. What operational modes of FTIR microspectroscopy is used to obtain the spectrum of the sheath?
The ATR mode
There are three operational modes of FTIR microspectroscopy. An issue with one of the operational mode is that the depth of penetration of the IR radiation into a fiber depends on the wavelength, so a correction should be applied to any obtained spectrum. What is this operational mode?
The ATR mode
Which of the following color test is the most commonly used for distance estimation between the muzzle and the target
The Griess test.
Which of the following reagents consists of a mixture of 2% vanillin and 1% acetaldehyde in ethanol?
The Duquenois reagent
Which of the following reagents consists of 10% KNO2 in sulfuric acid?
The Liebermann reagent
Which of the following statements about fluorescence and phosphorescence is false?
The energy of phosphorescence is more than the energy of fluorescence.
A generic mass spectrometer has four components and ICP corresponds to
The ion source
Which of the following statements is NOT true for attenuated total reflectance?
The penetration depth is independent of the wavelength of light
The terms we use to describe combustions depends on characteristics such as the speed of the reaction. In the detonation of an explosive
The reaction front moves faster than the speed of sound
Which of the following statements about the refractive index (RI) is correct?
The speed of light in vacuum is faster than the speed of light in a given medium.
There are three operational modes of FTIR microspectroscopy. When the fiber is mounted on a KBr pellet, what is the mode of FTIR microspectroscopy is going to be conducted?
The transmission mode
Which of the following statement about SEM-EDS is false?
There is color information in the signal.
For qualitative analysis, simple preparations and cleanups are generally adequate.
True
What is NOT true about primary explosives?
They are very stable.
Readability of a volumetric flask is an example of uncertainty with
Triangular distribution
The marriage of a microscope with ______ is the simplest proposition because lenses, objectives, and other optical components can be made of the same material.
VIS spectroscopy
Which of the following statements are true regarding the effect of flame temperature on atomic absorbance and atomic emission spectroscopy?
Varying the flame temperature by 10 K affects the excited-state population of the analyte and will noticeably affect the analyte signal in atomic emission.
For normal phase SPE, which of the following solvent has the strongest eluting strength?
Water
Which of the following solvent has the weakest eluting strength in reversed phase liquid chromatography?
Water
Which of the following statements about control chart is correct?
Whenever a warning line is crossed, a second test is made
Infrared luminescence is used to:
a and b
The unconscious handwriting of two different individuals can never be identical because
all of above.
Reference blanks are primarily used to:
compensate for any absorbance due to reagents or contamination.
When a weak acid with one ionization center is dissolved in water at a concentration higher than 100 times of its Ka, which of the following equation can be used to calculate the pH of its solution?
pH= 1/2 (pKa-logC)
For drugs or other large molecules with a single weak-base site, the relationship between pH and its dissociative products can be calculated using
pH=pKa+log ([Base])/([Conjugate Acid ])
