Machine-translated by Google. Questions are authored in English.
Top

Forensic Instrumentation and Spectroscopy Questions and Answers

71.

Light that has all its waves pulsating in unison is called

Exam Year(s)

UGC NET - 2012,

Answer: B

Light whose waves all pulsate in unison, that is, in phase, is called laser light. This coherence, with the same wavelength and direction, is what separates a laser from an ordinary lamp.

A maser is the corresponding device for microwaves, not for light. Monochromatic light has a single wavelength but its waves need not be in step with each other. Polychromatic light holds many wavelengths, so its waves cannot be in unison. The word laser stands for light amplification by stimulated emission of radiation, and the coherence it describes is why a laser beam stays narrow over a long distance.

Please log in or register to report this question.

Discuss in Forum
72.

Hollow Cathode Lamp (HCL) is used in the following :

Exam Year(s)

UGC NET - 2012,

Answer: A

A hollow cathode lamp is the light source used in an atomic absorption spectrometer. Its cathode is made of the metal to be determined, so the lamp emits the sharp lines characteristic of that element, which the atoms in the flame absorb.

An atomic emission spectrometer uses the excited sample itself as a source, so it needs no lamp of this kind. Infrared spectrometers use sources such as a Nernst glower or globar, and X-ray fluorescence uses an X-ray tube. None of these uses a hollow cathode lamp. Each lamp holds only one metal or a few, so an analyst has to change the lamp for every element that is being determined, which is a known limit of the method.

Please log in or register to report this question.

Discuss in Forum
73.

Deviations from Beer's Law fall into which categories ?

Exam Year(s)

UGC NET - 2012,

Answer: D

Deviations from Beer's law fall into all the categories listed: real, instrumental and chemical. Real deviations come from the law itself, which holds only for dilute solutions, where changes in refractive index at high concentration matter. Instrumental deviations come from polychromatic light and stray radiation. Chemical deviations arise when the absorbing species associates, dissociates or reacts with the solvent.

So no single category is the whole answer and 'all of the above' is correct, which excludes the choices naming only real, instrumental or chemical.

Please log in or register to report this question.

Discuss in Forum
74.

Chromatography was first reported by

Exam Year(s)

UGC NET - 2012,

Answer: A

The keyed answer is Ramsey. In forensic texts on gas chromatography it is stated that the use of chromatographic separation was first reported by Ramsey in 1905, who separated mixtures of gases and vapours by adsorption on charcoal, and Tswett followed in 1906 with the separation of plant pigments, who is also commonly credited with the first chromatographic separation. Of the four names given, Henry, Pascal and Leduce are not linked with this work, so A is the only answer that the key can support.

Please log in or register to report this question.

Discuss in Forum
75.

Within a monochrometer, the necessary collimation and focussing are performed by :

Exam Year(s)

UGC NET - 2012,

Answer: A

Within a monochromator the necessary collimation and focussing are done by mirrors. The light from the entrance slit is made parallel by a collimating mirror, falls on the dispersing element, and the dispersed light is focused on the exit slit by a second mirror. Prisms (C) are used for dispersion in some instruments but they are not the part that collimates and focusses, detectors (B) and photo tubes (D) measure the intensity of the light and do not shape the beam. So A is correct.

Please log in or register to report this question.

Discuss in Forum
76.

Match the instrument with the detector.

List - IList - II
i. Atomic Absorption Spectrometera. Thermal conductivity
ii. Infra Red Spectrometerb. Hypersensitive Photoplate
iii. Emission Spectrographc. Golay
iv. Gas liquid Chromatographyd. Photomultiplier Tube

Exam Year(s)

UGC NET - 2012,

Answer: A

The gas liquid chromatograph uses a thermal conductivity detector (a-iv), the emission spectrograph records on a hypersensitive photoplate (b-iii), the infra red spectrometer uses a Golay detector, a pneumatic thermal detector (c-ii), and the atomic absorption spectrometer uses a photomultiplier tube (d-i). So the code is iv, iii, ii, i, option A. Options B, C and D put the photomultiplier tube or the photoplate with the wrong instrument, for example the Golay cell with the emission spectrograph.

Please log in or register to report this question.

Discuss in Forum
77.

Optical components in UV spectrometer are made up of :

Exam Year(s)

UGC NET - 2012,

Answer: B

The optical components of a UV spectrometer are made of quartz. Ordinary glass absorbs ultraviolet light below about 300 nm and plastic absorbs it too, so neither can be used for lenses, prisms and cells in the UV region, while quartz (fused silica) is transparent down to about 200 nm. Sodium halide material is used in the infra red region, as in rock salt windows. So B is correct. The sample cells for ultraviolet spectrometry are also made of quartz, and the lamps used as sources have a quartz envelope, since glass would absorb the radiation that is to be measured. Sodium chloride and other halide salts transmit in the infra red region, not in the ultraviolet, and plastic is not clear to ultraviolet light, so the answer is B.

Please log in or register to report this question.

Discuss in Forum
78.

Radioactivity of a substance can be measured by

Exam Year(s)

UGC NET - 2012, UGC NET - 2013,

Answer: D

The radioactivity of a substance is measured by a Geiger Muller counter, which detects the ionisation caused in a gas by alpha, beta or gamma radiation as an electrical pulse. TCD, the thermal conductivity detector, MCT, the mercury cadmium telluride infra red detector, and ECD, the electron capture detector, are detectors used in gas chromatography and infra red spectroscopy, and they do not count radioactive emissions in this way, though the ECD uses a radioactive source. So D is correct.

Please log in or register to report this question.

Discuss in Forum
79.

Following column packing materials are available in HPLC :

Exam Year(s)

UGC NET - 2012,

Answer: D

All of the packing materials named are available for HPLC columns. Microporous particles are small porous particles of silica, pellicular packings have a thin porous layer on a solid glass bead core, and bonded phase packings have a stationary phase chemically bonded to the support. Since A, B and C are each used, the answer is D, all of the above. Microporous packings are porous silica particles of fine size, pellicular packings are glass or metal beads with a thin porous layer on the surface and are used in the early liquid chromatography, and bonded phase packings have a stationary liquid chemically attached to the silica surface, which is the most widely used kind today. All three are therefore available.

Please log in or register to report this question.

Discuss in Forum
80.

The image seen through a compound microscope is

Exam Year(s)

UGC NET - 2012,

Answer: A

The image seen through a compound microscope is virtual. The objective forms a real, magnified image inside the tube, and the eyepiece works as a magnifying glass on it, so the final image the eye sees is virtual, enlarged and inverted compared with the object.

Real is wrong, since the final image cannot be thrown on a screen. False and Imaginary are not standard terms in optics; imaginary is only a loose way of saying virtual, so the key takes the exact word, virtual.

Please log in or register to report this question.

Discuss in Forum
Loading…

Topics

Other Subjects

Tags: Forensic Instrumentation and Spectroscopy Questions and Answers

About Us

ExamsRepo

Copyright © 2026 ExamsRepo . All Rights Reserved . With