Trace Evidence Examination Questions and Answers

81.

The range of lime (CaO) is within ______ in Portland cement.

A.30 - 35%
B.35 - 55%
C.60 - 67%
D.70 - 75%

Exam Year(s)

UGC NET - 2013,

Answer: C

Lime (CaO) makes up about 60 to 67 per cent of Portland cement, the largest single component, with silica, alumina and iron oxide forming most of the rest.

The ranges 30 to 35 and 35 to 55 per cent are too low, and 70 to 75 per cent is too high for the oxide analysis of ordinary Portland cement. The balance is made up of silica at roughly 17 to 25 per cent, alumina at 3 to 8 per cent, iron oxide at 0.5 to 6 per cent and small amounts of magnesia and sulphur trioxide, which is why lime is the dominant oxide.

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82.

In density gradient determination method of soil examination, the following liquids are commonly used :

A.Bromoform
B.Bromobenzene
C.Nitrobenzene
D.Mixture of bromoform and bromobenzene

Exam Year(s)

UGC NET - 2013,

Answer: D

In the density gradient method of soil examination a column is built from a mixture of bromoform and bromobenzene. Their densities are different, so blending them in graded proportions gives a smooth gradient in which soil particles settle at the level matching their own density.

Bromoform or bromobenzene alone, or nitrobenzene alone, would give a single density rather than a gradient, so a mixture is needed.

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83.

Match the following pertaining to paint sample :

List - I (Paint Pigment)	List - II (Colour of Paint)
a. Titanium Dioxide	i. Red
b. Cobalt Salt	ii. Blue
c. Graphite	iii. White
d. Lead tetra-oxide	iv. Black

Codes : a b c d

A.iii ii i iv
B.iv ii iii i
C.ii i iii iv
D.iii ii iv i

Exam Year(s)

UGC NET - 2013,

Answer: D

The correct pairing is a-iii, b-ii, c-iv, d-i. Titanium dioxide is the common white pigment, cobalt salts give blue, graphite is black, and lead tetroxide (red lead) is red.

The other code strings give titanium dioxide a non-white colour or make graphite red or white, which does not match the properties of these pigments. Pigment identification of this kind helps in comparing a paint chip from a scene with a suspect surface, because the pigment mixture and its colour give a class characteristic.

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84.

Fibers obtained from animals or plants may also be called as

A.Synthetic fiber
B.Natural fiber
C.Manmade fiber
D.Regenerated fiber

Exam Year(s)

UGC NET - 2013,

Answer: B

Fibres obtained from animals (wool, silk) or plants (cotton, jute, flax) are called natural fibres. Synthetic and manmade fibres are produced from chemicals, as nylon and polyester are, and regenerated fibres such as rayon are made by reprocessing cellulose from wood pulp. So natural fibre is the right term.

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85.

Which of the following fiber is of mineral origin ?

A.Mohair
B.Cashmere
C.Asbestos
D.Rayon

Exam Year(s)

UGC NET - 2013,

Answer: C

Asbestos is a fibrous silicate mineral, so it is a fibre of mineral origin. Mohair (from the Angora goat) and cashmere (from the Kashmir goat) are animal fibres, while rayon is a regenerated cellulose fibre made by chemical processing of plant material. Only asbestos is a mineral fibre.

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86.

Match the following in the soil as per Munsell colour Test :

List - I (Mineral)	List - II (Colour)
a. Hematite	i. Pale brown
b. Iron sulphide	ii. White
c. Calcite	iii. Red
d. Dolomite	iv. Black

Codes : a b c d

A.iii i iv ii
B.iii iv ii i
C.iii ii iv i
D.ii iii i iv

Exam Year(s)

UGC NET - 2013,

Answer: B

The Munsell soil colour match is hematite red (iii), iron sulphide black (iv), calcite white (ii) and dolomite pale brown (i). Hematite is the red iron oxide, the iron sulphide is black, calcite is a white carbonate and dolomite is pale in colour. So the sequence iii, iv, ii, i is right, and the other options exchange two or more of these colours.

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87.

_______ is a super cooled liquid which has attained so high viscosity as to be considered as solid.

A.Plastics
B.Glass
C.Acrylic fiber
D.Rayon

Exam Year(s)

UGC NET - 2013,

Answer: B

Glass is a super cooled liquid that has become so viscous that it behaves as a solid, since it has no regular crystalline structure and no sharp melting point. Plastics are polymers, acrylic fibre is a synthetic polymer fibre and rayon is a regenerated cellulose fibre, and none of them is described this way. So glass is the answer.

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88.

Besides silica, the main constituent of Gypsum soil is

A.Calcium carbonate
B.Calcium sulphate
C.Ferric oxide
D.Aluminium oxide

Exam Year(s)

UGC NET - 2013,

Answer: B

Gypsum is hydrated calcium sulphate, so beside silica a gypsum soil is mainly calcium sulphate. Calcium carbonate is the chief constituent of calcareous soil, and ferric oxide and aluminium oxide are typical of lateritic soils. So calcium sulphate is the answer.

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89.

The Refractive Index of glass can be determined by

(a) Beckeline method
(b) Abbe's refractometer
(c) GRIM
(d) Pulfritch refractometer
Codes :

A.(b) and (c) are correct.
B.(d) and (c) are correct.
C.(a) and (c) are correct.
D.(b) and (d) are correct.

Exam Year(s)

UGC NET - 2013,

Answer: C

The refractive index of glass fragments is found by the Becke line method (a matching of the index of the glass with an immersion liquid under the microscope) and by GRIM, the glass refractive index measurement system that automates it. Abbe and Pulfrich refractometers need larger specimens with polished surfaces and are not the routine forensic methods for small fragments, so the key accepts (a) and (c).

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90.

Medullary Index of human hair is

A.0.8
B.0.6
C.0.4
D.0.3 or below

Exam Year(s)

UGC NET - 2013,

Answer: D

The medullary index of human hair is 0.3 or below. The medullary index is the ratio of the diameter of the medulla to the diameter of the whole hair shaft. In humans the medulla is thin or absent, so the ratio is less than about one third, whereas animal hairs have a wide medulla with an index of 0.5 or more (often much more). The values 0.8, 0.6 and 0.4 are all too high for human hair and would point to an animal source, so option D is correct.

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