Note: This whole section is a part of Forensic Chemistry MCQs that includes topics such are arson, petroleum, and explosive products. These are made specifically for the preparation of NTA UGC NET and University entrance tests.
1. Arson is
- Fire due to accident
- Fire caused deliberately with malicious intention
- Fire caused by Diwali Fireworks
- Bush Fires Caused By lighting
Answer and Explanation
Answer: (2) Fire caused deliberately with malicious intention
Explanation: Interesting stats related to arson:
-> Types of arson motives: identified are->cause of 33% of dormitory fires and 15% of residential fires.
2. Which of the following is the most common cause of arson?
- Insurance fraud
- Pyromania
- Revenge
- Vandalism
Answer and Explanation
Answer: (3) Revenge
Explanation: As per the Office of Justice Program, the following are the stats that were the motive behind arson:
-> Revenge, 52.9%
-> Vandalism (deliberate destruction of or damage to public or private property.): 12.3%
-> Pyromania (serious mental health condition characterized by intentionally and repetitively setting fires): 10.1%
-> Fraud: Insurance fraud: 6.55%, Welfare fraud: 6.55%
-> Crime concealment: 2.9%
-> Psycho firesetter, 8.7%
Reference: OPJ.GOV
3. The correct sequence of events of the firing process in order of occurrence is
- Free burning, incipient, smoldering
- Smoldering, free burning, incipient
- Free burning, smoldering, incipient
- Incipient, free burning, smoldering
Answer and Explanation
Answer: (4) Incipient, free burning, smoldering
Explanation: Four stages of fires:
-> Incipient phase: the initial stage of fire characterized by preheating or pre-ignition, or both.
-> Emergent smoldering phase: combustion becomes increasingly pronounced and could pass directly to the fourth stage i.e. oxygen-related smoldering. eg: smoldering curtains or mattress fire.
-> Free burning phase: burning of material or structure in presence of adequate oxygen.
-> Oxygen-Related Smoldering: the final phase of burning. Flames cease leaving behind dense smoke and heat (if in a confined space).
Reference Book: Forensic Science by Nordby
4. The fundamental chemical reaction for fire initiation is
- Hydroxylation
- Oxidation
- Combustion
- Ignition
Answer and Explanation
Answer: (2) Oxidation
Explanation: Rapid oxidation is the initial fundamental chemical reaction that is required to evolve the heat and light in the presence of fuel and this process is called combustion.
Reference Book: Criminalistics: An Introduction to Forensic Science by Richard Safertsten
5. An oxidation-reduction reaction involved a change in the____________ state of a molecule
- Chemical
- Physical
- Oxidation
- Precipitation
Answer and Explanation
Answer: (3) Oxidation
Explanation: In an oxidation-reduction (redox) reaction there is a change in the oxidation state between the elements.
-> Substance getting reduced in a chemical reaction is known as an oxidizing agent
-> Substance getting oxidized is known as a reducing agent.
6. Debris material collected from arson crime scene should be packed in
- Sealed paper bag
- Plastic bag
- Cloth bag
- Metal box with a tight lid
Answer and Explanation
Answer: (4) Metal box with a tight lid
Explanation: Debris material collected from the arson crime scene should be packed in a metal box with a tight lid that helps in holding the volatile compound vapors that are crucial for GC analysis.
7. The minimum temperature at which a volatile compound forms flammable vapors that can ignite from an external source is called
- Fire Point
- Flash Point
- Ignition point
- Pout Point
Answer
Answer: (2) Flash Point
8. The lowest temperature at which a volatile compound forms enough flammable vapor that on ignition from an external source, its burning continues
- Fire Point
- Flash Point
- Ignition point
- Pout Point
Answer
Answer: (1) Fire Point
9. Assertion (A): Flashpoint of a liquid is always greater than the fire point
Reason (R): Fire points need more external heat to form enough vapors to continue burning.
- Both (A) and (R) are correct
- Both (A) and (R) are wrong
- Only (A) is correct and (R) is wrong
- Only (R) is correct and (A) is wrong
Answer and Explanation
Answer: (4) Only (R) is correct and (A) is wrong
Correct Assertion: Fire point is always greater than flashpoint because it needs more energy to form enough vapors that continue burning.
10. The temperature at which a volatile compound forms an ignitable vapor mixture in the air that burns by an external source for 5 seconds or less is considered to be:
- Fire Point
- Flash Point
- Ignition point
- Pout Point
Answer and Explanation
Answer: (2) Flash Point
Explanation: When an ignitable vapor mixture burns for less than 5 seconds (because of inefficient vapors) by an external source, that temperature is called a flashpoint. However, if vapors are more than enough that initiate a continuous burning, that minimum temperature is called fire point.
11. Which of the following apparatus is used for the determination of flashpoints?
- Cleveland open cup
- Pensky Martin closed the cup
- Abel apparatus
- All of the above
Answer and Explanation
Answer: (4) All of the above
Explanation: -> Abel Apparatus: It is suitable for materials whose flashes below 70°C
-> Pensky Martin closed the cup: all petroleum products whose flash point is more than 48.9°C.
-> Cleveland Open cup: Igniting above 175°F (79°C). It lacks precision and gives a higher flash point value than the original.
12. Which of the following apparatus has equilibrium between ignitable vapors with liquid?
- Close up Flashpoint Apparatus
- Open up Flashpoint Apparatus
- Equilibrium Flashpoint apparatus
- Both (1) and (2)
Answer and Explanation
Answer: (2) Open Up Flashpoint Apparatus
Explanation: Open Up Flashpoint Apparatus: Here liquid and vapors are in an open cup and flame is introduced at set intervals to know the flashpoint.
-> Close Up Flash Point Apparatus: Liquid and vapors are sealed in a cup and flame are introduced through the lid of the cup.
13. Which of the following apparatus are used to determine the fire point of a petroleum product?
- Cleveland open cup
- Knocking open cup
- CMT
- Both (1) and (2)
Answer and Explanation
Answer: (1) Cleveland Open Cup
Explanation: Nearly all-flash point apparatus can be used to determine the fire point of a petroleum product.
14. The lowest temperature at which a volatile material ignites itself without the help of any external flame or ignition source is called
- Fire Point
- Flash Point
- Ignition point
- Pout Point
Answer and Explanation
Answer: (3) Ignition Point
Explanation:
-> Ignition point is also called auto-ignition point.
-> Ignition temperature is always greater than fire point and flashpoint.
15. Arrange the following in descending order of temperatures.
- Fire point> Flash Point> Ignition point
- Flash Point> Ignition point> Fire point
- Ignition point> Fire point> Flash point
- Ignition point> Flash point> Fire point
Answer
Answer: (3) Ignition point> Fire point> Flash point
16. What is the flashpoint of highly flammable petroleum products?
- Flashpoint below 0°C
- Flashpoint below 21°C
- Flashpoint below 55°C
- All of the above
Answer and Explanation
Answer: (2) Flashpoint below 21°C
Explanation: Petroleum products can be divided into three categories based on flashpoints.
-> Extremely Flammable: Flashpoint below 0°C
-> Highly Flammable: Flashpoint below 21°C
-> Flammable: Flashpoint below 55°C
17. Which of the following patterns at the point of origin of fire indicates the possibility of interior fire?
- O pattern
- L pattern
- V pattern
- T pattern
Answer
Answer: (3) V Pattern
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check question 9. the answer and explanation do not match
Hi Junaid, I didn’t find any irrelevancy in the explanation. Don’t confuse fire point with flashpoint.
Q15 The answer is in descending order
Yes you’re correct.