Mock Test Set-20 (Forensic Science)

Q1. Which of the following is a major disadvantage of GC-MS despite its high specificity and accuracy?

A. It cannot separate mixtures

B. It cannot detect organic compounds

C. It requires compounds to be vaporized

D. It is incapable of compound identification

Answer: C. It requires compounds to be vaporized

Explanation: GC-MS (Gas Chromatography-Mass Spectrometry) necessitates that analytes be volatile or made volatile, which limits its application for thermally labile or high-boiling substances.

Q2. Which toxic gas binds hemoglobin with significantly higher affinity than oxygen and leads to cellular hypoxia?

A. Cyanide

B. Nitric oxide

C. Carbon monoxide

D. Sulfur dioxide

Answer: C. Carbon monoxide

Explanation: Carbon monoxide binds hemoglobin 200–250 times more strongly than oxygen, impairing oxygen delivery and leading to tissue hypoxia.

Q3. In forensic analysis of clandestine drug labs, which method is best suited to quantitate the controlled substance using internal standards?

A. Serial dilution method

B. Standard addition method

C. Relative response method

D. Colorimetric titration

Answer: C. Relative response method

Explanation: The relative response method uses internal standards to compare known and unknown samples via GC, providing reliable quantification.

Q4. Which instrumental technique is most sensitive to variations due to sample preparation?

A. GC-MS

B. FTIR

C. UV-Vis spectroscopy

D. HPLC

Answer: A. GC-MS

Explanation: GC-MS spectra are susceptible to variation in sample preparation methods, impacting reproducibility and accuracy of identification.

Q5. Which method is capable of distinguishing polymorphic forms of compounds such as titanium dioxide in paint?

A. FTIR spectroscopy

B. SEM-EDS

C. X-ray diffraction

D. UV-visible spectrophotometry

Answer: C. X-ray diffraction

Explanation: XRD identifies crystal structure and polymorphs, useful in discriminating phases in materials like titanium dioxide, especially relevant in paint analysis.

Q6. What is the optimal method for metal analysis in forensic toxicology due to its sensitivity and specificity?

A. Colorimetric assay

B. Atomic absorption spectroscopy

C. Electrochemical titration

D. Gas chromatography

Answer: B. Atomic absorption spectroscopy

Explanation: Atomic absorption spectroscopy is considered optimal for quantitative trace metal analysis in forensic toxicology due to its high specificity and sensitivity.

Q7. Which of the following drugs has a fatal blood concentration as low as 0.0033 µg/mL?

A. Cocaine

B. Digoxin

C. Methaqualone

D. Fentanyl

Answer: B. Digoxin

Explanation: Digoxin’s toxicity is potent at extremely low levels, with fatalities reported at blood concentrations as low as 0.0033 µg/mL.

Q8. What is the principle of the presumptive "spot" test in forensic drug analysis?

A. Isolation through GC-MS

B. Structural elucidation by spectroscopy

C. Color change upon reaction with a specific reagent

D. Flame emission of specific wavelengths

Answer: C. Color change upon reaction with a specific reagent

Explanation: Spot tests are simple colorimetric assays that provide preliminary evidence for the presence of specific classes of drugs. Positive results require confirmatory tests.

Q9. In hair comparison, which of the following is considered a Level III characteristic?

A. General pattern (loop/arch/whorl)

B. Ridge path

C. Pore shape and size

D. Bifurcations

Answer: C. Pore shape and size

Explanation: Level III fingerprint features, and similarly in hair, involve microscopic features such as ridge pores and sweat gland openings — highly individualized traits used in advanced comparison.

Q10. Which of the following statements is TRUE about LC-MS in forensic analysis?

A. LC-MS is less expensive than GC-MS

B. LC-MS can analyze only volatile compounds

C. LC-MS provides higher resolution than GC-MS

D. LC-MS is compatible with nearly all organic compounds

Answer: D. LC-MS is compatible with nearly all organic compounds

Explanation: LC-MS bypasses the need to vaporize the analyte, making it applicable to a broader range of organic compounds compared to GC-MS, which limits high-boiling or thermolabile analytes