Chapter 13: Metals, Paint & Soil
The emission spectrograph is used to determine the: A. Elemental composition of a substance. B. Crystalline structure of a substance. C. Mass of a substance. D. Weight of a substance.
A. Elemental composition of a substance.
A "fingerprint" of an element is obtained by the technique of: A. Emission spectroscopy. B. Ultraviolet spectrophotometry. C. Gas chromatography. D. Infrared spectrophotometry.
A. Emission spectroscopy.
Which would be LEAST useful in identifying a mineral crystal? A. Size B. Refractive index C. Color D. Geometric shape
A. Size
Which is NOT part of the composition of paint? A. Pigment B. Adhesive C. Binder D. Solvent
B. Adhesive
Which of the following statements is correct? A. All atoms of an element have the same atomic mass number. B. All atoms of an element have the same number of protons. C. All atoms of an electron have the same number of neutrons. D. All atoms of an element have an equal number of neutrons and electrons.
B. All atoms of an element have the same number of protons.
Automobile finishes typically contain which layer(s)? A. Colorcoat B. An electrocoat primer, colorcoat, and clearcoat C. Electrocoat primer and colorcoat D. Clearcoat
B. An electrocoat primer, colorcoat, and clearcoat
Paint as physical evidence is most frequently encountered in: A. Burglary. B. A hit-and-run. C. Car theft. D. Both A and B
B. A hit-and-run.
Which coating helps resist UV radiation and acid rain? A. Clearcoat B. Basecoat C. Primer surface D. Electrocoat primer
B. Basecoat
In neutron activation analysis, an element is identified by measuring the energy of emitting: A. Electrons. B. Gamma rays. C. Protons. D. Neutrons.
B. Gamma rays.
Neutron activation analysis involves bombarding specimens with neutrons and then measuring the resultant: A. Alpha particles. B. Gamma rays. C. X-rays. D. Beta particles.
B. Gamma rays.
The nucleus of an atom contains: A. Protons and electrons. B. Protons and neutrons. C. Neutrons. D. Neutrons and electrons.
B. Protons and neutrons.
The polymeric makeup of paint binders can readily be compared by: A. Emission spectroscopy. B. Pyrolysis gas chromatography. C. Microscopy. D. Thin-layer chromatography.
B. Pyrolysis gas chromatography.
Paint chips may be individualized to a single source by examining their: A. Relative size. B. Pyrograms. C. Color and layer structure. D. Ultraviolet spectra. E. Infrared spectra.
C. Color and layer structure.
Which property imparts paint with its most distinctive forensic characteristics? A. Gloss B. Texture C. Color-layer sequence D. Color
C. Color-layer sequence
What is the logical first step in soil analysis? A. Examination for presence of debris under low-power magnification B. Examination of minerals and rocks under high-power magnification C. Comparison of dried soil sample for color and texture D. Use of the density-gradient tube technique
C. Comparison of dried soil sample for color and texture
Which coating provides resistance to corrosion? A. Clearcoat B. Primer surface C. Electrocoat primer D. Basecoat
C. Electrocoat primer
Gamma rays are: A. Neutrons. B. Electrons. C. Electromagnetic radiation. D. Protons.
C. Electromagnetic radiation.
An element is selective in the frequency of light it will absorb. This selectivity is due to its: A. Number of neutrons. B. Atomic mass. C. Electron energy levels. D. Proton cloud.
C. Electron energy levels.
Atoms having the same atomic number but different atomic masses are called: A. Isotherms. B. Isobars. C. Isotopes. D. Isomers.
C. Isotopes.
The ________ properties of crystals, such as refractive index and birefringence, provide points of identification that help characterize them. A. Physical B. Amorphous C. Optical D. Chemical
C. Optical
The most abundant element of the earth's crust is: A. Carbon. B. Hydrogen. C. Oxygen. D. Aluminum.
C. Oxygen.
Which of the following statements is false? A. The neutron has no electrical charge. B. The proton has a charge of +1. C. The electron and proton have the same mass. D. Protons and neutron comprise the nucleus of an atom.
C. The electron and proton have the same mass.
After examining small paint chips from an auto accident scene and using the PDQ database, the crime lab worker can determine the ________ of the vehicle. A. Make B. Model C. Year D. All of the above
D. All of the above
Radioactivity is composed of: A. Gamma rays. B. Beta particles. C. Alpha particles. D. All of the above
D. All of the above
What type of evidence would be expected to have trace elements? A. Glass and metal objects B. Soil and gun primer particles C. Paint and bullet fragments D. All of the above
D. All of the above
Which coat represents the "eye appeal"? A. Electrocoat primer B. Clearcoat C. Primer surface D. Basecoat
D. Basecoat
Paint binders can be chemically analyzed using: A. TLC. B. Pyrolysis GC. C. IR spectrophotometry. D. Both B and C
D. Both B and C
In a simple emission spectrograph, excitation of the specimen under investigation is accomplished with a(n): A. Inductive magnetic field. B. Activated prism. C. Hot plasma torch. D. Electrical arc.
D. Electrical arc.
The atoms of hydrogen, deuterium, and tritium all have the same number of protons, but differ in the number of neutrons they possess. These substances are: A. Elements. B. Compounds. C. Molecules. D. Isotopes.
D. Isotopes.
A continuous spectrum is most helpful in identifying a particular element because it serves as a unique "fingerprint" of an element. True or False
False
All atoms of an element have the same number of neutrons. True or False
False
Alpha particles are a form of radiation consisting of electrons. True or False
False
Emission spectroscopy measures the frequency of light emitted by an atom when one of its electrons moves to a higher orbital. True or False
False
If soil is found adhering to an object, the investigator should remove the soil particles from the object and send them to the laboratory. True or False
False
Isotopes are atoms of the same element that have different numbers of protons in their respective nuclei. True or False
False
It is not necessary that the collected paint from a vehicle involved in a hit-and-run accident be close to the area of the car suspected of being in contact with the victim. True or False
False
Surface texture is the most important of the characteristics that a criminalist looks for when comparing paint chips. True or False
False
The first step in a forensic soil comparison is analysis of the size of the particles. True or False
False
The minerals found in different soil samples cannot effectively be used to determine whether or not they have the same origin. True or False
False
The number of protons in the nucleus of an atom is called the atomic mass number. True or False
False
After the paint has been applied to a surface, the solvent evaporates. True or False
True
An atom has a net zero electrical charge, which indicates that it contains the same number of protons and electrons. True or False
True
Gamma rays are a high-energy form of electromagnetic radiation. True or False
True
Isotopes have different atomic mass numbers. True or False
True
Neutrons carry no charge. True or False
True
The concentration of the absorbing element is directly proportional to the quantity of the light absorbed. True or False
True
The investigator should not try to remove trace paint evidence found on a tool but package the tool for laboratory examination instead. True or False
True
The variety of coatings applied to the body of an automobile adds significant diversity to automobile paint and contributes to the forensic significance of automobile paint comparisons. True or False
True
Standard/reference soil samples should be collected at the site of the crime at various intervals within a 100-foot radius of the crime scene. True or False
True