Question 1

Which of the following may be used as an accelerant?
A) gasoline
B) dynamite
C) cotton fiber
D) chlorine gas

Accepted Answer

Gasoline is a commonly used accelerant in arson cases as it is easily ignitable and can spread quickly. Dynamite is an explosive and not an accelerant. Cotton fiber is a material and cannot be used as an accelerant. Chlorine gas is toxic and not commonly used in arson cases.

Question 2

Combustion on the surface of a solid fuel in the absence of heat high enough to pyrolyze the fuel as observed with coals or a cigarette is termed: ____.
A) spontaneous combustion
B) smoldering combustion
C) heat of combustion
D) glowing combustion

Accepted Answer

Smoldering combustion is a slow, low-temperature flameless form of combustion that occurs on the surface of a solid fuel in the absence of heat high enough to pyrolyze the fuel, as observed with coals or a cigarette. Spontaneous combustion refers to a self-ignition process that occurs without an external ignition source, while heat of combustion refers to the energy released during a complete combustion reaction. Glowing combustion refers to the presence of visible red or orange glowing of a fuel surface indicating the high temperature of the fuel.

Question 3

Which of the following must the CSI investigate upon arriving at a suspected arson scene?
A) search for streamers
B) potential debris with accelerant
C) locate point of origin
D) time-delay device
E) all of the above

Accepted Answer

All of the above are crucial elements to investigate in a suspected arson scene: search for streamers to determine if the fire was intentionally set, potential debris with accelerant to identify the type of accelerant used, locate point of origin to determine how the fire started and where it began, and time-delay device to determine if the arsonist used a device to start the fire.

Question 4

What type of packaging container is recommended for arson evidence?
A) Paper fold
B) Zip-lock closed plastic bags
C) Sealed paper bags
D) Sealed metal paint cans

Accepted Answer

Sealed metal paint cans are the recommended container for arson evidence as they are airtight, sturdy, and can withstand high temperatures. They also prevent any potential ignition or contamination of evidence. Paper fold, zip-lock plastic bags, and sealed paper bags are not recommended as they can tear, puncture, or allow for contamination of evidence.

Question 5

The ion mobility spectrophotometer is a ____ test for explosives residues.
A) presumptive
B) confirmatory

Accepted Answer

The ion mobility spectrophotometer is a presumptive test for explosives residues because it detects the presence of specific compounds associated with explosives, but it does not actually identify the specific explosive material. A confirmatory test would be necessary to positively identify the explosive material present.

Question 6

A TATP explosion produces large quantities of heat and gas.

Accepted Answer

TATP (triacetone triperoxide) explosion produces large amounts of heat and gas due to the rapid decomposition of the compound.

Question 7

In a(n) ___ case, you expect to find a crater.
A) explosion
B) burglary
C) arson
D) murder

Accepted Answer

A crater is typically formed as a result of an explosion, so if the question mentions the expectation of finding a crater, the most likely scenario would be an explosion. The other options, burglary, arson, and murder, would not typically result in a crater formation.

Question 8

A ____ is a chemical explosion in which the reaction front moves through the explosive at greater than 1000 m/s.
A) low
B) medium
C) high

Accepted Answer

A "high" chemical explosion refers to a detonation, which is defined as a rapid and violent exothermic reaction where the reaction front moves through the explosive material faster than the speed of sound in that substance. This results in a shock wave that can cause significant damage and destruction. Detonations are typically associated with high explosives such as TNT, C-4, and dynamite.

Question 9

A liquid burns at the ____ when the temperature is high enough to vaporize it.
A) ignition temperature
B) spontaneous combustion
C) pyrolysis point
D) flash point
E) heat of combustion

Accepted Answer

The flash point is the lowest temperature at which a liquid gives off enough vapor to form an ignitable mixture with air near the surface of the liquid. This means that the liquid will burn when the temperature is high enough to vaporize it and create a flame, which is consistent with the given statement.

Question 10

Which of the following is a low explosive?
A) black powder
B) TNT
C) ANFO
D) PETN

Accepted Answer

Black powder is a low explosive because it burns quickly rather than detonating, and therefore has a slower and less powerful explosion compared to high explosives like TNT, ANFO, and PETN.

Question 11

Explosion initiators include electrical current from____.
A) clock switch
B) battery
C) automobile engine switch
D) watch
E) all of the above

Accepted Answer

Explosion initiators can be triggered by an electrical current from various sources, including a clock switch, battery, automobile engine switch, and even a watch, as all these devices can provide the necessary electrical impulse to initiate an explosion.

Question 12

In order to start a fire, heat, fuel and ____ are required.
A) wood
B) lighter fluid
C) gasoline
D) oxygen

Accepted Answer

Oxygen is required to start a fire as it supports combustion by reacting with the fuel and producing heat. The other choices (wood, lighter fluid, gasoline) are all types of fuel that can be used once the fire has started, but they do not themselves cause the ignition.

Question 13

What is the first phase in a fire's progression?
A) incipient
B) free burning
C) growth
D) oxygen-regulated smoldering

Accepted Answer

The incipient phase is the first phase of a fire's progression, characterized by a small flame or smoke that may not yet be visible but can be detected by a heat source or other means.

Question 14

Where is the fire's greatest damage?
A) the lowest point
B) the point of origin
C) the ceiling
D) the point at which the fire was extinguished

Accepted Answer

The point of origin is where the fire started and therefore the area that is likely to have experienced the greatest damage.

Question 15

An analyst compared a mixture of methyl ethyl ketone, lighter fluid and gasoline to an unknown accelerant from an arson scene. Which of the following techniques would be best for the comparison of the two samples?
A) UV-Vis spectroscopy
B) TLC
C) fluorescence spectroscopy
D) gas chromatography

Accepted Answer

Gas chromatography would be the best choice to compare the two samples as it is a highly sensitive technique used for separating and analyzing volatile compounds in a mixture. This would allow for the identification and comparison of specific compounds in both the unknown accelerant and the mixture of methyl ethyl ketone, lighter fluid, and gasoline. The other techniques listed (UV-Vis spectroscopy, TLC, and fluorescence spectroscopy) are either not ideal for separating volatile compounds or not specific enough for this type of comparison.

Question 16

For which sample is solid phase microextraction (SPME) often used?
A) arson / accelerant
B) body fluid / DNA
C) drug material / cocaine
D) none of the above

Accepted Answer

Solid phase microextraction (SPME) is often used for arson investigation and analysis of accelerants.

Question 17

Explain how you would process a crime scene of suspected arson in terms of the evidence to collect and what to look for in processing. What can help you to determine if the crime was arson or not?

Accepted Answer

The answer of Explain how you would process a crime...

Question 18

Briefly explain how you can use the GC spectrum to determine that a sample is an accelerant and the class / type of accelerant present.

Accepted Answer

The answer of Briefly explain how you can use the...

Question 19

What evidence would you seek to collect in an investigation of an intentional explosion?

Accepted Answer

The answer of What evidence would you seek to collect...

Question 20

What chemical technique(s) would be appropriate to use to determine the identity of an explosive?

Accepted Answer

The answer of What chemical technique(s) would be appropriate to...

Quiz 14: Arson and Explosives

Which of the following may be used as an accelerant?

Combustion on the surface of a solid fuel in the absence of heat high enough to pyrolyze the fuel as observed with coals or a cigarette is termed: ____.

Which of the following must the CSI investigate upon arriving at a suspected arson scene?

What type of packaging container is recommended for arson evidence?

The ion mobility spectrophotometer is a ____ test for explosives residues.

A TATP explosion produces large quantities of heat and gas.

In a(n) ___ case, you expect to find a crater.

A ____ is a chemical explosion in which the reaction front moves through the explosive at greater than 1000 m/s.

A liquid burns at the ____ when the temperature is high enough to vaporize it.

Which of the following is a low explosive?

Explosion initiators include electrical current from____.

In order to start a fire, heat, fuel and ____ are required.

What is the first phase in a fire's progression?

Where is the fire's greatest damage?

An analyst compared a mixture of methyl ethyl ketone, lighter fluid and gasoline to an unknown accelerant from an arson scene. Which of the following techniques would be best for the comparison of the two samples?

For which sample is solid phase microextraction (SPME) often used?

Explain how you would process a crime scene of suspected arson in terms of the evidence to collect and what to look for in processing. What can help you to determine if the crime was arson or not?

Briefly explain how you can use the GC spectrum to determine that a sample is an accelerant and the class / type of accelerant present.

What evidence would you seek to collect in an investigation of an intentional explosion?

What chemical technique(s) would be appropriate to use to determine the identity of an explosive?