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1. All of the following are true about the importance of GSR in firearm investigation, EXCEPT
- It can determine the range of fire
- It can identify a firearm injury
- It can ascertain the common source of ammunition under all conditions
- It can help in identifying the shooter
Answer
Answer (3): It can ascertain the common source of ammunition under all conditions
2. A lady was found dead at a crime scene with a revolver in her hand. In order to decide whether she had committed suicide or it is a case of homicide, gunshot residue may be lifted by taking hand swabs with 5% nitric acid. The swabs are taken by :
- Cotton with the help of glass rods, dried and sealed in glass tubes.
- Cotton with the help of glass rods, dried and sealed in cellophane envelopes.
- Cotton with the help of plastic rods, dried and sealed in glass tubes.
- Cotton with the help of plastic rods, dried and sealed in cellophane envelopes.
Answer and Explanation
Answer: (4) Cotton with the help of plastic rods, dried and sealed in cellophane envelopes.
3. Which of the following is the correct method of collection of gun-shot residue from the hands of a person suspected to have committed suicide by a pistol?
- Swabs by 5% nitric acid are taken by glass rods and preserved in glass bottles.
- Swabs by 5% nitric acid are taken by wooden sticks and preserved in glass bottles.
- Swabs by 5% nitric acid are taken by Johnson’s buds and preserved in glass bottles.
- Swabs by 5% nitric acid are taken by Johnson’s buds and preserved in cellophane envelopes.
Answer and Explanation
Answer: (4) Swabs by 5% nitric acid are taken by Johnson’s buds and preserved in cellophane envelopes.
4. In gun-shot residues, a walker test is done for detection of :
- Nitrate
- Nitrite
- Lead
- Antimony
Answer and Explanation
Answer: (2) Nitrite
Explanation: Walker test is performed for the detection of nitrites (bright red color).
5. Walker’s test for GSR is used for the detection of:
- Nitrate
- Carbon monoxide
- Carbon dioxide
- Nitrite
Answer and Explanation
Answer: (4) Nitrite
Explanation: In the walker’s test, GSR particles on photographic paper + immersed in a solution of 5% 2-naphthylamine- 4, 8-disulphonic acid> Air dried> Wetted with 20% Acetic Acid= Any bright red spot is the indication of nitrite compounds.
6. In Walker’s test, the acetic acid vapors convert nitrites into:
- Nitrates
- Nitric oxide
- Nitrous acid
- Nitrous oxide
Answer and Explanation
Answer: (3) Nitrous acid
Explanation: In the walker’s test,
-> GSR particles on photographic paper + immersed in a solution of 5% 2-naphthylamine- 4, 8-disulphonic acid, then,
-> Sample is made to air-dried and lastly,
-> Wetted with 20% acetic acid that converts the nitrite into nitrous acid.
-> Any bright red spot is an indication of nitrite compounds.
8. Dermal nitrate test detects
- Nitric acid poisoning
- Bloodstain
- Gunshot residue
- Both (1) and (3)
Answer
Answer: (3) Gunshot residue
7. Dermal nitrate test for GSR is used for the detection of the following:
- Carbon dioxide
- Nitrite
- Nitrate
- Both (2) and (3)
Answer and Explanation
Answer: (4) Both (2) and (3)
Explanation:
-> Dermal Nitrate Test is a presumptive test for the GSR based on the detection of unburned nitrates and nitrites by the formation of nitrate ions.
-> Also called: Paraffin test, Diphenylamine test.
-> Introduced by Teodoro Gonzalez of Criminal Identification Laboratory, in 1993.
-> Procedure: hand is first coated with paraffin. after cooling, the cast is removed and treated with diphenylamine (acidic).
-> Result: Blue flecks in paraffin cast.
Source: Gunshot Wounds: Practical Aspects of Firearms, Ballistics, and Forensic Techniques. Ch-12.
9. Assertion (A): Ricochet bullet causes a keyhole entry.
Reason (R): The bullet tumbles after hitting an intermediate object.
- (A) is true, but (R) is false
- (R) is true, but (A) is false
- Both (A) and (R) are true
- Both (A) and (R) are false
Answer and Explanation
Answer: (3) Both (A) and (R) are true
Explanation: Tumbling bullet is responsible for keyhole entry and the following are the cause
-> Rifling in the barrel could be worn out, therefore it does not impart enough spin to the bullet while it is leaving the barrel.
-> Undersized bullet not engaging to the rifling.
-> Non-adequate twist rate as per weight, the shape of the bullet.
-> Damage to barrel
-> Hit something in between (Ricochet bullet)
10. Match the following
| List-I | List-II |
| (a) Griess Test | (i) Infrared Photography |
| (b) Empty cartridge case at the scene of occurrence | (ii) Pistol |
| (c) Powder pattern | (iii) Shotgun |
| (d) Wads at the scene of Occurrence | (iv) Presence of nitrite |
| (a) | (b) | (c) | (d) | |
| 1. | (iii) | (ii) | (i) | (iv) |
| 2. | (iv) | (ii) | (i) | (iii) |
| 3. | (i) | (ii) | (iii) | (iv) |
| 4. | (ii) | (iii) | (i) | (iv) |
Answer and Explanation
Answer: (2) (iv), (ii), (i), (iii)
Explanation:
-> Griess test is an analytical chemistry test that is used to detect the presence of nitrite ion in a given sample by imparting red-pink coloration.
-> Powder patterns can be easily seen using infrared photography.
11. Which of the following tests help to detect nitrites in gunshot residue?
- Teichman
- Precipitin
- Maiti
- Thematic appreciation
Answer and Explanation
Answer: (3) Maiti
Explanation:For nitrites, there are two basic tests such as the Walker test (Griess test) and the Maiti tests.
-> In the Maiti test, blue specks on the yellow background of photo paper are the indication of nitrites.
-> In the Walker test, bright-red-orange color is the indication of nitrites.
12. The modified Griess Test is specific for the determination of ________ in gunpowder residue.
- Nitrate
- Antimony
- Barium
- Nitrite
Answer and Explanation
Answer: (4) Nitrite
Explanation: Modified Griess test is also an analytical chemistry test for the detection of nitrite ions just like the Griess test. The main difference between the Griess and Modified Griess test is— the Modified version doesn’t use Marshall’s Reagent [N-(1-naphthyl)-ethylenediamine dihydrochloride] which is carcinogenic in nature.
13. Assertion (A): The presence of blackening around a suspected gun-shot hole on dark-colored clothes can be revealed by infrared photography.
Reason (R): This is so when the dye of the clothes is not too opaque to infrared rays whereas the blackening is. The photograph gives the required contrast.
- (A) is correct, but (R) is wrong
- Both (A) and (R) are wrong.
- Both (A) and (R) are correct.
- (A) is wrong, but (R) is correct.
Answer and Explanation
Answer: (3) Both (A) and (R) are correct.
14. Which element around gunshot hole is tested by dithiooxamide test
- Copper
- Lead
- Tin
- Aluminium
Answer and Explanation
Answer: (1) Copper
Explanation: Dithiooxamide Test (also known as the Rubeanic Acid Test) is a chemically specific test for the presence of cuprous (copper) compounds. They are generally used for the detection of copper-bearing particulates (bullet jacket fragments) found around the bullet hole.
15. Blackening around gun-shot holes in clothes, means:
- Deposit of smoke
- Deposit of lead vapours
- Deposit of black powder
- Lead ring/ Dirt ring around the hole
Answer and Explanation
Answer: All are correct
16. Which of the following is used to analyze for the presence of gunshot residue?
- Microspectrophotometry
- Refractive index measurement
- Polarized light microscopy
- Scanning electron microscopy coupled with energy dispersive X-ray analyzer
Answer and Explanation
Answer: (4) Scanning Electron Microscopy coupled with energy dispersive X-ray analyzer
Explanation: Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectroscopy (EDS or EDX) is a vital tool to depict the elemental analysis of the sample.
-> Combined, they are majorly used for elemental analysis of inorganic compounds such as barium, lead, and antimony.
-> Specifically to SEM, it helps to analyze both morphological information and the elemental composition of particles.
17. Statement (S1): Walker’s test gives pink colour on the swabs collected from the area suspected to have firearm discharge residue.
Statement (S2): The pink colour is due to the presence of nitrite in the firearm discharge residue.
- S1 is correct but S2 is not correct
- Both S1 and S2 are correct.
- S1 is not correct but S2 is correct
- Both S1 and S2 are not correct
Answer and Explanation
Answer: (3) S1 is not correct but S2 is correct
Explanation: Walker’s Test for Gunshot residue: Detection of nitrite on clothing.
-> GSR on cloth + pretreated photographic paper with sulfanilic acid and alpha-naphthylamine = Orange-red color.
18. Neutron activation analysis detects the presence of the following in G.S.R
- Antimony and lead
- Antimony and barium
- Barium and nitrites
- Antimony and nitrites
Answer and Explanation
Answer: (2) Antimony and barium
Explanation: Neutron activation analysis (NAA) is used for the detection of barium and antimony in the GSR samples.
-> The detection is measured as the form of the isotopes of barium and antimony (139Ba and 122Sb).
19. Match List I with List II
| List I | List Il |
| (a) GSR on the cast treated with diphenylamine dissolved in sulphuric acid | (i) Orange ring indicates the presence of antimony |
| (b) GSR on test cloth treated with 1 drop of triphenyl methyl arsonium iodide alcoholic solution (10%) | (ii) Pink-coloured specks indicate nitrite particles |
| (c) GSR on filter paper, moistened with acetic acid, is sprayed with a solution of 2 naphthylamine sulphanilic acid and nitric acid | (iii) Pinkish violet (scarlet) colour indicates the presence of lead |
| (d) GSR on cloth piece moistened with 1% HCL treated with sodium rhodizonate solution | (iv) Blue colour spots indicate the presence of nitrates |
| (a) | (b) | (c) | (d) | |
| 1. | (i) | (iv) | (iii) | (ii) |
| 2. | (ii) | (iii) | (iv) | (i) |
| 3. | (iii) | (ii) | (i) | (iv) |
| 4. | (iv) | (i) | (ii) | (iii) |
Answer and Explanation
Answer: (4) (iv), (i), (ii), (iii)
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