UGC NTA NET/JRF Exam, Forensic Science, January-2025

Total Questions: 100

51. Arrange the components of explosive train in the correct order.

A. Detonating
B. Primer
C. Flash
D. Booster
E. Base Charge
Choose the correct answer from the options given below:

1. B, D, A, C, E
2. B, А, C, D. E
3. C. D, A, B, E
4. D, C, В, A, E

Correct Answer: 2. B, А, C, D. E

Solution:

The explosive train consists of components arranged from the weakest initiating charge to the most powerful main charge:
C. Flash: the smallest initiating spark/flame.
B. Primer: sensitive charge that receives energy from flash.
D. Booster: an intermediate charge that amplifies primer's output.
A. Detonating: a stronger transfer stage for reliable initiation.
E. Base charge: the main explosive, hardest to initiate, delivers destructive power.
So, the correct sequence is Flash → Primer → Booster → Detonating → Base Charge.

52. Which of the following are true statements of explosion chemistry?

A. Deflagration is when explosion speed is less than the speed of sound.
B. Detonation is when explosion speed is greater than the speed of sound.
C. Condensed explosives are gaseous in nature.
D. Dispersed explosives are solid in nature.
E. Thermal explosion is produced when a liquid meets to another hot liquid and rapidly reaches to boiling point.
Choose the correct answer from the options given below:

1. A, C, D, E
2. A, B, Е
3. А, C, Е
4. A, B, D, E

Correct Answer: 2. A, B, Е

Solution:

A. Deflagration: correct - it is subsonic burning (< speed of sound).
B. Detonation: correct - supersonic shockwave (> speed of sound).
C. Condensed explosives are gaseous in nature: wrong - condensed explosives are solid or liquid.
D. Dispersed explosives are solid in nature: wrong - dispersed explosives are gaseous or vapor mixtures.
E. Thermal explosion: correct - occurs when two hot liquids contact and rapidly vaporize.

53. Important features for thin layer chromatography includes:

A. Adsorption chromatography.
B. Gypsum is used to bind the stationary phase.
C. Results are in terms of retention time.
D. N₂ is used for migration of the analyte of internet.
E. Solvent front is used for the calculation of the results.
Choose the correct answer from the options given below:

1. A, C and E only
2. B, C, D and E only
3. А, В and E only
4. A, C, D and E only

Correct Answer: 3. А, В and E only

Solution:

Thin Layer Chromatography (TLC) features: A. Adsorption chromatography: correct - separation is based on adsorption on stationary phase.

B. Gypsum used as binder: correct - gypsum/ plaster of Paris is added to silica/alumina to coat plates.

C. Results in terms of retention time: wrong - in TLC results are reported as Rf (retention factor), not time.

D. N₂ used for migration: wrong - analyte migrates by capillary action of solvent, not nitrogen gas.

E. Solvent front is used for result calculation: correct - Rf = distance travelled by compound ÷ distance travelled by solvent front.

54. What information about a paint sample can be obtained by use of Infrared Micro Spectrophotometry?

A. Colour of the paint
B. Chemical component of the paint
C. Thickness of the paint
D. Functional group present in paint
E. No. of coating of the paint
Choose the correct answer from the options given below:

1. B, D only
2. C, A only
3. В, С only
4. D, A only

Correct Answer: 1. B, D only

Solution:

Infrared Microspectrophotometry gives chemical composition and functional groups in paint layers:
B. Chemical component of paint: correct.
D. Functional groups present in paint: correct. Other options (colour, thickness, no. of coatings) are obtained by microscopy, SEM, or visual analysis, not IR spectra.

55. Molotov Cocktail is made with following components:

A. Glass bottle
B. Ignitable liquid
C. Cloth soaked in accelerant
D. Primer
E. Nitroglycerine
Choose the correct answer from the options given below:

1. A, D and E only
2. B, C, D and E only
3. А, B and C only
4. A, C and D only

Correct Answer: 3. А, B and C only

Solution:

A Molotov Cocktail is an improvised incendiary device consisting of:
A. Glass bottle (container).
B. Ignitable liquid (like petrol, kerosene, alcohol).
C. Cloth wick soaked in accelerant, stuffed in bottle neck and ignited before throwing.
It does not use primers or nitroglycerine, since it is a crude firebomb, not a military explosive.

56. Match the LIST-I with LIST-II.

LIST-I (Explosives)	LIST-II (Common name)
A. RDX	I. Cordite
B. HMX	II. Gun cotton
C. Dynamite	III. Hexogen
D. Nitrocellulose	IV. Octagen

Choose the correct answer from the options given below:

1. A-III, B-IV, C-I, D-II
2. А-III, B-I, C-II, D-IV
3. A-II, B-III, C-I, D-IV
4. A-II, B-I, C-III, D-IV

Correct Answer: 1. A-III, B-IV, C-I, D-II

Solution:

Match the explosives with their common names:
A. RDX → III. Hexogen (RDX is commonly called Hexogen).
B. HMX → IV. Octagen (HMX is known as Octogen, more powerful than RDX).
C. Dynamite → I. Cordite is incorrect, since dynamite is nitroglycerin absorbed in kieselguhr, while Cordite is a smokeless propellant. However, from the given list, Cordite is the only pairing left, so Dynamite →I.
D. Nitrocellulose → II. Gun cotton (true; nitrated cellulose is guncotton).

57. Which element in the diatoms make them resistant against the acids?

1. Iron
2. Silica
3. Quartz
4. Cadmium

Correct Answer: 2. Silica

Solution:

The resistant property of diatoms comes from their frustules (cell walls) made of silica (SiO₂). Silica resists acid digestion, which is why diatoms persist in forensic tests even after strong acid treatment of tissue samples.

58. The outer most area of the hair is known as:

1. Cortex Fusi
2. Medulla
3. Cortex
4. Cuticle

Correct Answer: 4. Cuticle

Solution:

The hair shaft has three regions:
Medulla: central core.
Cortex: middle layer, contains pigment granules.
Cuticle: outermost layer, composed of overlapping transparent scales that protect the inner structures.
So, the outermost area of hair = Cuticle.

59. Which of the following methods is never used for the paint analysis?

1. Fluorescence microscopy
2. SEM-EDS
3. TEM
4. ESDA

Correct Answer: 4. ESDA

Solution:

Common methods for paint analysis:

Fluorescence microscopy: used to study paint layers and pigments.

SEM-EDS (Scanning Electron Microscopy with Energy Dispersive Spectroscopy): determines elemental composition.

TEM (Transmission Electron Microscopy): rarely used but possible for ultra-thin pigment/particle studies.

ESDA (Electrostatic Detection Apparatus): used for indented handwriting analysis, not paint analysis.

60. The automative finishing system for steel usually consists of at least four organic coating. Which is the first coat to be applied?

1. Base Coat
2. Primer surface
3. Electrocoat primer
4. Clear Coat

Correct Answer: 3. Electrocoat primer

Solution:

Automotive finishing on steel typically involves four coats:
1. Electrocoat primer (first coat): an anticorrosive undercoat applied by electrodeposition.
2. Primer surfacer.
3. Base coat (color).
4. Clear coat (protective gloss).
So, the first coat applied = Electrocoat primer.