Forensic Test 2
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gunshot residue is often analyzed using a microscope. typically, the microscope has an x-ray analyzer attached to it so that the elemental composition of the residue can be determined. The microscope used to do this is the
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scanning electron microscope
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which microscope is best suited to the study of birefringent minerals and fibers?
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polarizing microscope
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many samples of physical evidence are materials that are sensitive to heat. For example, organic explosive residues and certain drugs (such as LSD) are heat sensitive. Which chromatographic process would be the best technique to analyze organic explosives and heat sensitive drugs?
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high-pressure liquid chromatography (HPLC)
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Gas chromatography suffers a big drawback in that it does not produce specific identification of a compound. This problem is overcome by connecting the GC to a
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mass spectrometer
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(look at example) the part labeled B points
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body tube
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the line labeled C points to a
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objective lense
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the part labeled A points to the
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ocular lense
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the line labeled D points to a
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stage
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(look at diagram) shown below is a spectrum of heroin. What type of spectrum is it?
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infrared (IR) spectrum
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A parfocal microscope
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allows for ease of focus when switching from low to high power
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A particularly invaluable technique for distinguishing most paint formulas is
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pyrolysis gas chromatography
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**which of the following cannot be determined from microscopic examination of hair
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age of an individual
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The book fatal vision chronicled a famous investigation dealing with a 1979 crime that involved Jeffrey McDonald, a military physician. He was accused of
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killing his wife and two daughters
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in his defense Jeffery McDonald, a military physician, claimed that
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four intruders committed the crime he was accused of.
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as magnification of the compound microscope increased, the depth of field
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is decreased
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which microscope has the largest working distance and thus is useful for the examination of bulky items such as paint, soil, marijuana?
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stereoscopic microscope
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which property imparts paint with its most distinctive forensic characteristic?
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color-layer sequence
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(gas chromatograph) the part labeled in 4 in the diagram above is called the
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column
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gas chromatographs are use to seperate the components of a mixture. the part where the separation occurs is the part numbered
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4 (column)
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in the diagram above there is a box drawn around the part numbered 4. the box represents a
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oven
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tests used to identify specific illegal drugs or substances by the color and morphology of the crystals formed when the substance is mixed with specific reagents are known as
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microcrystalline tests
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(look at picture) given the cross-section of hair shown below, the most likely racial origin is
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asian origin
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the medullary index can be used to determine whether a hair is of animal or human origin. for humans, the index is
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generally less than one-third
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automobile paints are generally composed of four layers. the layer consisting of epoxy-modified polyesters that smooth out and hide any seams or imperfections is called the
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basecoat
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in which stage of hair growth doe stye hair generally fall from the scalp
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telegon
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in the diagram shown below one of the basic scale patterns of hair. the scale pattern is
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imbricate
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nuclear DNA typing can be most successfully accomplished on hairs that have been removed during which stage of growth
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anagen
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pigment granules that impart hair color are found in the
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cortex
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(diagram) the point labeled A is the
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cuticle
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the point labeled C is the
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medulla
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when hair is forcibly removed, a translucent piece of tissue surrounding the hair's shaft near the root may be present. this is shown as the
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follicular tag
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Wayne Williams, the Atlantic child murder, was convicted of murdering 2 young men, but it was though that he was responsible for the murder of
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28 male and 2 female african american children
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Wayne Williams conviction was unique because it was based primarily on
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fiber evidence found several of the victims.
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although there was no apparent connection between Wayne Williams and the victims, he was connected with the case when
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a police offer heard a \"splash\" in a river at a stakeout.
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although a flaming fire can be supported only by gaseous fuel, it some instances a fuel can burn without the presence of a flame. this known as
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glowing compulsion
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the amount of heat evolved when a substance is burned in oxygen is the heat
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heat of combustion
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The diagram shown below was drawn in class. It show the interaction of fuel with oxygen and varying distances
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...
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which microscope is best suited to the study of birefringent minerals and fibers?
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polarizing microscope.
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when forensically comparing hair, it is important to have representative sample to compare against. For head hair, how many hairs should be collected for a representative sample?
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fifty full-length hairs from all areas of the scalp.
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one of the common methods for identifying fibers is by measuring its
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refractive index
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a microscopic characteristic of a fiber that is used for comparison is
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all of the above
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the minimum temperature at which a liquid fuel will produce enough vapor to burn is called the
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flash point
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pigments granules that impart hair color are found in the
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cortex
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which of following is regenerated fiber?
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triacetate
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automobile paints are generally composed of four layers. the layer consisting of epoxy-modified polyesters that smooth out and hide any seams or imperfections is called the
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primer surfacer
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which type of spectroscopy is a rapid and reliable method for identifying the generic class of fiber?
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gas chromatographic spectroscopy.
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in which stage of hair growth does the hair generally fall from the scalp
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telegon
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for automobile paint, the layer that gives the paint its color is the
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basecoat
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by far the most prevalent plant fiber, which makes its evidential value almost meaningless, is
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cotton
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since 1995 the royal Canadian mounted police forensic labs have been systematically gathering color and chemical information on automotive paints. the data base is known as
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PDQ
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which of the following is a synthetic fiber?
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nylon
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when hair is forcibly removed, a translucent piece of tissue surrounding the hair's shaft near the root may be present. this is known as the
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follicular tag
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the concentrations at which a vapor-to-fuel mixture in the air is capable of burning is referred to as the
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flammable range
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although a flaming fire can be supported only by gaseous fuel, it some instances a fuel can burn without the presence of a flame. this is known as
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oxidative decomposition
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part of the evidence that was used to convict jeffrey mcdonald was
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81 blue fibers from a pajama top
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in his defense jeffrey mcdonald, a military physician, claimed that
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four intruders committed the crime of which he was accused.
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the book fatal vision chronicled a famous investigation dealing with 1979 crime that involved jeffrey mcdonald, a military physician. he was accused of
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killing his wife and two daughters
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the minimum temperature at which fuel will spontaneously ignite is called the
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ignition temperature
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synthetic fibers that are composed of a large number of atoms arranged in repeating units. the repeating units are called
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polymers
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synthetic fibers are often composed of large number of atoms arranged in repeating units. the repeating units are called
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monomers
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the primary suspect in the Atlanta child murders was
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wayne williams
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the Atlanta child murders involved the murder of
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28 african americans males and 2 african americans females
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ultimately the suspect was convicted of killing
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two adult male ex-convicts
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the event that led police to the suspect in the Atlanta child murders was
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a splash in a river below a bridge
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