Forensics Quizzes

In the analysis of explosives by IMS, ______ is employed as the "doping agent" to increase selectivity and reduce background interference.

Methylene chloride

Which of the following methods is able to differentiate d-cocaine/l-cocaine?

Microcrystal test

The total IR range extends from about 12,800 to 10 cm-1. The most frequently used IR range is

Mid-IR (4000 to 400 cm-1)

Which of the following statements for the absorption of light is true?

Molecules that absorb light are promoted to an excited state

The following dye is best categorized as

Nitro and nitroso (2 NO2 groups and 2 NH groups)

Which of the following drug is used as an inhalant?

Nitrous oxide

Which of the following statements is NOT true?

The color red in a fabric can be created by combining dyes that absorb combinations of magenta and yellow light.

For a compound microscope, as the magnification increase

The depth of focus decreases; the working distance decreases

As part of an apprenticeship, a trainee in a forensic chemistry laboratory is tasked with determining the concentration of cocaine in a white powder. The powder was prepared by the QA section of the laboratory and the accepted true value was 13.2%. However, the concentration of cocaine is not known to the trainee (who has a blind sample). The trainee's supervisor is given the same sample with the same constraints. The table in the following shows the result of 10 replicate analyses (n =10) made by the two chemists. Which of the calculated values is incorrect?

The forensic chemist's measurements has a relative error of 0.6%.

A fuel can only achieve combustion in:

The gaseous state.

The minimum temperature at which fuel vapor will ignite is known as:

The ignition temperature

Which of the following statements about blackbody is NOT true?

The maximum blackbody emission for an object near 300 K occurs at ultraviolet wavelengths.

Which is NOT true of the plasma atomic spectroscopy?

The plasma discharge acts like an intense continuous flame, generating extremely high temperatures over 10 000 K.

For a combustion reaction, the maximum heat will be generated when

The reaction mixture is at stoichiometric equivalence

There are three operational modes of FTIR microspectroscopy. When the fiber is mounted on a gold mirror, what is the mode of FTIR microspectroscopy is going to be conducted?

The reflection mode

The following shows the thermoplastic behavior of a polymer.

This polymer is amorphous.

Nylon 6 and nylon 6,6 are easily differentiated by their IR spectra.

True

One of the advantages of an SPE preparation over LLE method is that multiple solvents can be used to clean the sample before the final eluting solvent is added

True

In atomic absorption spectroscopy, we use ______ to produce narrow lines of the correct frequency.

hollow-cathode lamps

Which of the following monochromator terms is NOT correctly defined?

refraction: scattering of light by a prism

The following picture depicts that thin films of polymer are NOT made by

solution casting

Calculate the oxygen balance of aluminum metal (the atomic mass of aluminum and oxygen are 27.0 and 16.0, respectively).

-89%

When TLC is used to separate basic drugs, which of the following solvent system will give the separation better resolution?

Methanol/acetone/NH4OH

Which are important characteristics of a printer, photocopier, or fax machine?

All of the above

Which of the following professional organization offers certification of forensic toxicologists

American Board of Forensic Toxicology (ABFT)

Calculate the oxygen balance of ammonium nitrate (the molecular mass of ammonium nitrate and oxygen is 80.0 and 32.0, respectively).

+20%

Which of the following polymerization will keep going until the monomer is gone?

Anionic polymerization.

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 standard error of means.

0.17

Aspirin (MM=180.157) is an acidic drug, S0 = 1. grams/300mL water; pKa = 3.5. Calculate the solubility at pH 5.1 in both M and g/100 mL

0.76 M, 13.6g/100mL

A seizure of 369 1-kg bricks of a tan powder is received in a crime laboratory. All the bricks are carefully weighed, and it is determined that all weigh 1.00 kg ± 0.05 kg. The prosecuting attorney explains to the analyst that the penalty is more severe if controlled substances are found in the amount of more than 100.0 kg. If the analyte samples 10, analyzes them, and finds that all are positive. Using the hypergeometric function in Excel, the odds of a severe penalty is

1 in 6E+05

A drug analysis is performed with gas chromatography/mass spectrometry (GC/MS) and requires the use of reliable standards. The lab purchases a 1.0-mL commercial standard that is certified to contain the drug of interest at a concentration of 1.000 mg/mL with a reported uncertainty of 1.0%. To prepare the stock solution for the calibration, an analyst uses a syringe with an uncertainty of 0.5% to transfer 250.0 L of the commercial standard to a Class-A 250.0-mL volumetric flask with an uncertainty of 0.08 mL. Using the NUS portions of the NUSAP model, report the concentration of the diluted calibration solution.

1000. ± 11. ppb

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

2.2

Using the Springhall Roberts rules to predict the products of an explosion of picric acid (C6H3N3O7, molecular mass 229.1) and assuming ΔH° of picric acid is -245 kJ/mol, the relative explosive power (REP) of picric acid is subsequently calculated to be (the molar volume of a gas is 22.4 L)

2.5 kJL/g2

A .40 caliber pistol is loaded with a cartridge containing 3.2 grains of propellant which is rated at 3000 J/g. Assume that the chemical energy is converted to kinetic energy with 30% efficiency and the bullet weighs 100.0 grains, calculate the estimated muzzle velocity of the bullet. (1 g = 15.43 grains; 1 J = 1 kg m2 s-2)

240 m/s.

______ materials have more than one refractive index.

Anisotropic

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. Twenty two samples is collected and a presumptive test for heroin applied; 2 negatives are identified. Use the ENFSI spreadsheet to calculate how many additional samples, assuming that all of them are going to be positive after test, must be taken to be 90% confident that 90% of the seizure are heroin.

30

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

The dynamic reaction cell reduces isobaric interference with thermodynamically favorable reactions that remove interfering species with the same mass-to-charge ratio. Which of the reactions remove interfering specie for 52Cr+?

40Ar12C+ + NH3 → NH3+ + Ar + C

The standard ionization energy in EI is

70 eV

Consider a lens that has a focal length f of 25 mm: If an object is placed on the optic axis at a point 37.5 mm away, the image that comes into focus at

75 mm

By how many kilojoules per mole is the energy of O2 increased when it absorbs ultraviolet radiation with a wavelength of 147 nm (h = Planck's constant = 6.626 x 10-34 J-s; Avogadro number is 6.022 × 1023)?

814 kJ/mol

Determine the %ionization of a basic drug, pKa of 8.2, at physiological pH

86

Suppose a laboratory receives a seizure consisting of 800 white tablets, and half of these tablets are pure methamphetamine and half are lactose tablets, although the analyst does not know this. The analyst selects 10% of the tablets (80) at random for testing, what is the probability that half of these (40) are methamphetamine according to the hypergeometric approach in Excel?

9.4 %

Typical cotton contain nearly ___ cellulose.

90%

A solid phase extraction is illustrated as follows. Which compound has the greatest relative affinity for the stationary phase

A (elutes out last)

Which of the following statements about significant figures is correct?

A balance is used to weigh 1.2300 grams of powder. In this case, there are 5 significant figures

When the Liebermann reagent is added to a sample of cocaine HCl:

A color change is expected

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 core?

A combination of both

In a triple quadruple mass spectrometer, Q1 acts as

A mass filter

Which is NOT true for a photodiode array spectrophotometer?

A photodiode array spectrophotometer is a dispersive spectrometer.

Lactose (milk sugar) is a disaccharide derived from galactose and glucose joined with

A β-1-4' linkage

Which of the following are incorrect for Beers Law?

Absorbance decreases as pathlength increases.

Which of the statements about accuracy and precision is correct?

Accuracy is measured by %error.

The following paint binder is best categorized as

Acrylic. (methyl methacrylate to poly)

Which of the following fiber has negligible or undetectable birefringence?

Acrylonitrile

The pedigree of a reported result include

All of above

Which of the following statements about traceability is correct?

All of above statements are correct.

Which of the following statements about ICP/MS is true?

All of above statements are true.

The equilibrium constant for a partitioning, KD, depends on the relative affinity of an analyte for each phase. Which of the following will not affect the relative affinity?

All of above will affect the relative affinity

Telltale signs of arson include:

All of the above

When a lens is used to create a real image of an object, which of the following statements is correct?

As the object moves closer to the focal point of the lens from distance, the focal length of the lens does not change.

Which coat of an automatable paint represents the "eye appeal"?

Basecoat

The combustion continuum can be classified based on forensic application as fire, firearms and bombs. With regard to their speed of burn, which of them is characterized as a supersonic combustion reaction?

Bombs

Sodium rhodizonate is used to detect ______ in GSR.

Both b and c (barium and lead)

The following schematic illustrates a gas chromatography system. The capillary column is

C (the big box with the winding tubing)

Which of the following statements about the rifling of a gun barrel is NOT true?

Caliber is measured from the bottoms of the grooves.

The molecular weight of the polymerizing mixture jumps quickly in the production of a

Chain growth polymer.

Which of the following statement about forensic evidence is incorrect?

Circumstantial evidence is weak evidence.

When a suspect computer printer is not available, the examiner may need to analyze the document's _____ to identify the make and model of the machine.

Class characteristics

In a latex paint, film formation occurs mainly by ______ mechanism

Coagulation

Which of the following drug is a stimulant?

Cocaine

Cellulose can be placed in the category of

Condensation polymer.

Water being heated on a stove illustrates the concept of:

Convection

In the RGB color system, equal amount of B and G will produce

Cyan

Which of the following statements is true?

Cyan ink subtracts red light.

Which of the following samples can be prepared through extraction?

Drugs

Which of the following x-ray based analytical techniques is widely used in couple of SEM in elemental analysis of forensic samples?

Energy-dispersive spectrometry (EDS)

The following polymer is best categorized as

Epoxy resins (complex with benzene rings and 3-atom rings)

According to the CIE chromaticity diagram as shown, the dominant wavelength of color d is

Equal to 500 nm

For quantitative analysis, simple preparations and cleanups are generally adequate.

False

QA usually has to do with the procedures, policies, and practices designed to assure data quality.

False

To facilitate the detection of a problem in the stock solution, calibration checks (CC) are used. The following figure shows an ideal calibration check.

False

When collecting random samples, manual or arbitrary selection by the analyst is the best option.

False

X-ray fluorescence energies for the elements are dependent of the chemical form such Fe(0) in steel and Fe(VI) in Na2FeO4

False

A regression line is used to calibrate instruments and take the familiar form y = mx + b , where m is the slope and b is the y intercept. Which of the following statements with regard to the regression line is incorrect?

Forcing a least-squares regression curve through the origin, i.e. the point (0,0), is always recommended.

An officer submitting fire debris requests that you analyze it for the presence of gasoline with ethanol. Which of the following analytical technique would you use?

GC-MS

For the purpose of QA/QC in forensic chemistry, there are a few well-known abbreviations. Which detailed description of the abbreviation in the following is incorrect?

GLP: General Learning Program

The free-energy change of any reaction is defined in terms of enthalpy and entropy: G = H - TS. In all combustion reactions,

H is always negative and S is always positive

Which of the following units is NOT one of the major components in a dispersive IR instrument?

He-Ne laser

Which of the following sampling method is usually used to determine blood alcohol concentration?

Head space

Ionization energy of Ar is higher than those of all elements except

Helium

In order to extract heroin (pKa 7.6) and cocaine (pKa 8.6) from a sample, a reversed phase, nonpolar solid phase with cation exchange capability is used. Which of following steps is using an incorrect condition?

Hexane is used to elute the drugs.

A Cassegrain system uses ____________ to focus rays of UV, VIS, and IR energy and serves as an objective "lens" in microspectrophotometers.

Highly polished stainless-steel mirrors

Which of the following is able to atomize ions?

ICP

In fiber analysis, the forensic frame work is

Identification-classification-individualization

The MRM methodology used by LC-MSn cannot

Identify unknowns

Thin layer chromatography (TLC) is commonly employed in forensic analysis of

Inks

Which of the following printing produces depth and texture in the surface of the paper?

Intaglio printing

Which of the following analysis will be useful for geographic location of drug origin?

Isotope ratios of alkaloids

What is not uncertainty?

It disappears when an analyst on his or her best day.

Which of the following statements about CMY color system is NOT true?

It is referred to as an additive color system.

Which of the following ruling that extended the scope of the judge's gatekeeper role to all expert testimony, not just scientific?

Kumho Tire Co., Ltd. V. Carmichael

You are called to a fire scene in which the point of origin appears to be in a restroom in a high school. The dimensions of the room are 25'x10'x10'. In one corner, you find the burned remains of a small tank labeled acetylene that appears to have been stolen from the high school welding shop. You call the supplier and learn that the tank if full contained 25 lbs of acetylene. The lower flammable limit (LFL) and upper flammable limit (UFL) of acetylene is 2.5 and 81% by volume. Calculate LFL and UFL in in pounds and determine if a combustible mixture would be supported. Assume 1.0 atm pressure and a typical indoor temperature of 25°C. (MM of acetylene = 26.04; 1 cubic foot = 28.32 liter; 1 lb = 452.6 g; R = 0.082 L atm K-1 mol-1).

LFL = 4.2, UFL = 134.5, a combustion mixture would be supported.

Which of the following drug was used in psychotherapy?

LSD

Which of the following compound can be found in the primers of modern firearms?

Lead styphnate

The ease with which a child's handwriting can be individualized is _____ the ease with which one can individualize an adult's handwriting.

Less than

Which of the following substances is a diluent when it is present in illicit drugs?

Mannitol

According to ASTM classification, turpentine is ignitable liquid with

Medium carbon number

Which of the following drug was used by American soldiers from World War II through the first Gulf War in 1991?

Methamphetamine

The power of an explosive can be defined as VQ, where V is the volume of gaseous products and Q is the heat evolved. Assuming that conditions are such that methane (CH4, molecular mass 16) and methanol (CH3OH, molecular mass 32) combust via an explosion to have their maximum power, which of the following statement is correct?

Methane is approximately 4.9 times more powerful than methanol per gram detonated

An analyst proposes a new method for the analysis of blood alcohol. As part of a method validation study, she analyzes a blind sample 5 times and obtains the following results: 0.055%, 0.054%, 0.055%, 0.052%, and 0.056%. Based on Grubbs test, are there any outliers in the data?

No

According to the Rules and Regulations under the Textile Fiber Productions Identification Act, the definition for a manufactured fiber is that the fiber-forming substance is a long-chain synthetic polyamide in which less than 85 percent of the amide linkages are attached directly to two aliphatic groups. The name of this fiber is

Nylon

Which of the following statements is FALSE?

Once adulthood is reached, an individual's handwriting generally will not change with age.

Cotton fibers are easily identified by

PLM

Which of the following statements about the collection of paint evidence involved in hit-and-run incidents is NOT true?

Paint smeared or embedded in garments or objects may be picked up with a pair of tweezers.

Which of following ion or molecule will have the longest max in its UV/VIS spectrum?

Phenoxide ion

Which of the following atomic spectroscopic technique has the best linear range?

Plasma mass spectrometry.

The polymer with the following monomer and repeating unit is

Polyethylene (CH2-CH2 repeated)

The polymer with the following monomer and repeating unit is

Polypropylene (CH2-CH2-CH2 repeated)

Which are common chemical ingredients of black powder?

Potassium nitrate, charcoal, sulfur

High explosives can be classified as either _____ or _____ explosives.

Primary; secondary

In the CIE chromaticity diagram, which of the following color is not a spectral color?

Purple

What is the decomposition of organic matter by heat?

Pyrolysis

Which of the following chromatographic techniques is most widely used in fiber analysis?

Pyrolysis GC

The following compound is

RDX (6 N's...3 in a ring, and 3 NO2 groups off the ring)

Potassium persulfate is an initiator for

Radical polymerization.

In the analysis of explosives, which of the following methods has the ability to probe materials through containers?

Raman spectroscopy

With paints, which of the following analytical techniques has the advantage that binders and resins contribute minimal interference, allowing for characterization of the pigment?

Raman spectroscopy

According to the Rules and Regulations under the Textile Fiber Productions Identification Act, the definition for a manufactured fiber is that it composed of regenerated cellulose in which substituents have replaced not more than 15 percent of the hydrogens of the hydroxyl groups. The name of this fiber is

Rayon

Which of the following materials is not categorized as natural fiber?

Rayon

In atomic spectroscopy, which of the following statements is NOT true for chemical interference?

Releasing agents preferentially react with the analyte.

Consider a GC/MS analysis of a drug sample extract that, based on initial presumptive tests and screening, is thought to contain heroin. A batch in the analysis would likely contain a few types of quality assurance samples. Which of the following description about the quality assurance samples is incorrect?

Replicate: is the term used to describe samples collected outside of the laboratory but from the same source or population.

Which of the following analytical technique is the most preferred method for gunshot residue (GSR) analysis?

SEM-EDX

Which of the following sample preparation method is particularly amenable to the extraction and preconcentration of accelerants in fire debris samples using headspace method?

SPME

If a controlled substance has some accepted medical use with restrictions, it is in

Schedule II

Which of the following analytical techniques can be used in DNA typing?

Slab gel electrophoresis

Which is a natural heat-producing process that may give rise to a fire?

Spontaneous combustion

Which of the following analytical method cannot be categorized as definitive identification

TLC

Which of the following ruling that gave judges what is referred to as a gatekeeper in determining admissibility?

The Daubert Decision

Which of the following reagents consists of 2% formaldehyde in sulfuric acid?

The Marquis reagent

The quantity of heat from a chemical reaction comes from:

The breaking and formation of chemical bonds.

Robustness is a measure of a method's capacity to remain unaffected by small but deliberate variations in method parameters; provides an indication of its reliability during normal use.

True

Which of the following electromagnetic radiation can promote electrons in a molecule but does not eject them from the molecule?

UV/Vis

Which of the following drug is a depressant?

Valium

Which of the following light have the highest energy?

Violet

Which of the following statements for light modeled as a wave is NOT true?

Wavelength is the distance between the crest and the trough of the waves.

Which of the following statements about the refraction angles is correct?

When light is traveling from glass to air, the refraction angle air > glass.

Which of the following statements is true regarding each component in creating an interferogram?

When the moveable mirror travels a distance of /4, deconstructive interference occurs.

Which of the following statements about control chart is correct?

Whenever an action line is crossed, the equipment is removed from service.

Steel surfaces of a car are protected from corrosion by galvanization with

Zinc

All of the following are used as extender pigments except

ZnCrO4

Graphite furnace employs temperature programming to produce elemental vapor. The furnace is purged with Ar or N2 during

all of the steps except the atomizing step

The following water solubility curve describes

an acidic drug (low solubility at low pH, high solubility at high pH)

In paper manufacturing, the beating state can

association fiber with water

In an ion mobility spectrometer, a soft ionization occurs via interactions with ______ emitted by a 63Ni source.

beta particles

Which of the following polymers can contribute to the acidity of paper?

lignin

Which of the following provides an estimate of lipid solubility?

logP

The common air/acetylene flame in atomic absorbance spectroscopy gives temperatures of approximately

over 2000 K

When a weak base with one ionization center is dissolved in water at a concentration higher than 100 times of its Kb, which of the following equation can be used to calculate the pH of its solution?

pH= 1/2 (pKw+pKa+logC)

The rms noise is ____________ than the peak-to-peak noise.

~5 times less