Forensic Science and Physical Evidence Questions and Answers

Answer: A

Maharashtra's first forensic science laboratory was started in 1958.

The Forensic Science Laboratory at Mumbai (then Bombay) was set up in 1958 and grew into the Directorate of Forensic Science Laboratories, Maharashtra, which now runs regional laboratories across the state.

The later years in the options, 1966, 1981 and 1989, fall in the period when regional laboratories were being added, not when the first laboratory was founded.

Answer: D

The key's answer is the polar coordinate method.

In the polar coordinate method the sketcher fixes one reference point and records each item by its angle (measured with a compass or transit) and its distance from that point. Because it needs only one known point, it suits large open outdoor scenes, where there may be no walls or fixed objects to measure from.

Triangulation is also used outdoors but needs two fixed reference points for every item. The baseline method suits long, narrow scenes or rooms, and photogrammetry is a photographic measuring technique rather than a sketching method.

Answer: A

The most suitable reagent for steel is Fry's reagent.

When a serial number is stamped into metal, the metal beneath the stamp is strained, and the strained zone dissolves at a different rate from the surrounding metal. Etching an erased area with a suitable reagent can therefore bring the obliterated number back into view.

Fry's reagent, a solution of cupric chloride in hydrochloric acid and water, is the standard etching reagent for iron and steel. Other reagents suit other metals, for example Villela's reagent for some stainless steels and different solutions for aluminium and brass, so Fry's is the general choice for steel surfaces.

Answer: B

The pitch pattern of a sentence is called intonation.

Intonation is the rise and fall of pitch across a phrase or sentence, which signals questions, statements, emphasis and emotion. In forensic speaker comparison, a speaker's habitual intonation patterns are among the features examined.

The fundamental frequency is the physical rate of vibration of the vocal folds at any one moment, which is heard as pitch; intonation is its pattern over the sentence. Timbre is voice quality, the property that makes two voices at the same pitch sound different, and phonology is the study of a language's sound system.

Answer: A

A narrow band spectrogram is best for studying harmonics.

A spectrogram's analysis bandwidth sets a trade-off between frequency and time resolution. A narrow band filter (around 45 Hz) resolves frequency finely, so the individual harmonics of the voice appear as separate horizontal lines and their movement shows the pitch contour.

A wide band filter (around 300 Hz) blurs the harmonics together but resolves time finely, so it shows formants as dark bands and individual glottal pulses as vertical striations. Amplitude is shown by darkness on both kinds.

Answer: D

The slow film is ISO 25/15–50/80, the paper's misprint for ISO 25/15° to 50/18°.

A film's ISO speed measures its sensitivity to light, and each rating is given in two forms, an arithmetic number (25, 100, 400) and a logarithmic degree value (15°, 21°, 27°). Slow films, ISO 25 to 50, need more light but give fine grain and high resolution, which suits copying documents and close-up evidence photography.

ISO 100 to 200 is medium speed, while ISO 400 to 500 and ISO 800 to 3200 are fast films for low light, with coarser grain.

Answer: B

Protection of life and personal liberty is guaranteed by Article 21.

Article 21 says that no person shall be deprived of his life or personal liberty except according to procedure established by law. Since the Maneka Gandhi case (1978) the procedure must be just, fair and reasonable, and the courts have read many rights into it, such as privacy and a speedy trial. It applies to every person, citizens and non-citizens alike.

Article 19 guarantees freedoms such as speech and movement, Article 20 protects against ex post facto laws, double jeopardy and self-incrimination, and Article 22 protects against arbitrary arrest and detention.

Answer: C

The process is cracking.

Crude oil contains more heavy, high-boiling fractions than the market needs, and fewer of the light fractions that make up petrol. Cracking, thermal or catalytic, breaks the large hydrocarbon molecules of the heavy fractions into smaller ones, raising the yield of gasoline.

Polymerization and alkylation do the opposite, joining small molecules into larger ones in the gasoline range, and isomerization rearranges straight-chain molecules into branched ones to raise the octane number. None of them splits large molecules.

Answer: B

These access methods are digital protocols used in cell phones.

Mobile phone networks share radio channels among many users by multiple access schemes. TDMA (Time Division Multiple Access) gives each user a time slot on a frequency, as in GSM, and CDMA, which the paper calls 'Collision Detection Multiple Access', gives each user a unique code (Code Division Multiple Access), as in the cdmaOne and CDMA2000 networks.

Mobile phone forensics needs to know which technology a handset uses. PDAs, CCTV systems and workstations are not defined by these cellular access protocols.

Answer: B

The document is NABL-113.

The National Accreditation Board for Testing and Calibration Laboratories accredits laboratories against ISO/IEC 17025, and publishes field-specific criteria that add requirements for each discipline. NABL 113 sets out the specific criteria for accreditation of forensic science laboratories, covering areas such as chain of custody, evidence handling and the different forensic disciplines.

The other numbers are criteria documents for other kinds of laboratory; NABL 112, for example, covers medical laboratories.