Questions Set-1_Instruments based Questions

Instrument Based Questions

Q1. The gas carrier phase is used in

i.        HPLC

ii.      Atomic Absorption Spectrophotometer

iii.     GCMS

iv.     GLC

a.      iii. and iv. are correct

b.      i. and ii. are correct

c.       ii. And iii. are correct

d.      i. and iv. are correct

ANSWER:

a.       iii and iv are correct

EXPLANATION:

Gas-Liquid Chromatography (GLC) utilizes a gas carrier phase to carry the sample through the chromatographic column, where it interacts with the stationary liquid phase.

Gas Chromatography-Mass Spectrometry (GCMS) also employs a gas carrier phase to transport the sample through the chromatographic column before entering the mass spectrometer for detection and analysis.

High-Performance Liquid Chromatography (HPLC) typically uses a liquid carrier phase instead of a gas, and Atomic Absorption Spectrophotometry (AAS) does not involve the use of a carrier phase; instead, it relies on the absorption of specific wavelengths of light by analytes in solution.

Q2. FID detector in GLC is most suitable for the detection of

a.      Gasoline

b.      Insecticide

c.       Alkaloids

d.      Barbiturates

ANSWER:

a.       Gasoline

EXPLANATION:

The Flame Ionization Detector (FID) is a commonly used detector in gas chromatography, particularly for the analysis of organic compounds. It is highly sensitive to hydrocarbons and is especially suitable for detecting compounds such as gasoline, which primarily consists of hydrocarbons.

While insecticides, alkaloids, and barbiturates are also organic compounds, the FID is particularly effective for detecting hydrocarbons like those found in gasoline due to its high sensitivity to carbon-containing compounds.

Q3. A current which will exist even if no light is falling on the U­V is detectors is known as

a.      Dark current

b.      False current

c.       True current

d.      Pseudo current

ANSWER:

a. Dark current

EXPLANATION:

Dark current is the current that flows through a photodetector even when no light is falling on it. This current is typically caused by thermal excitation of charge carriers within the detector material or other sources of noise. Dark current can impact the sensitivity and performance of the photodetector, particularly in low-light conditions, and it needs to be properly accounted for in measurements to ensure accuracy.

Q4. Exciter filter is a part of the following microscope:

a.      Polarising microscope

b.      Phase contrast microscope

c.       Fluorescence microscope

d.      Transmission electron microscope

ANSWER:

c. fluorescence microscope

EXPLANATION:

An exciter filter is a crucial component of a fluorescence microscope. In fluorescence microscopy, the exciter filter is used to select the specific wavelengths of light that will excite the fluorophores present in the sample. These fluorophores then emit light at longer wavelengths, which can be visualized to produce fluorescence images. The exciter filter ensures that only the desired excitation wavelengths reach the sample, enhancing the specificity and sensitivity of fluorescence imaging.

Q5. _____ is used as neutron moderator in NAA in TRIGA reactor.

a.      Water

b.      Ethanol

c.       Chloroform

d.      Acetone

ANSWER:

a. Water

EXPLANATION:

In Neutron Activation Analysis (NAA) conducted in TRIGA (Training, Research, Isotope Production, General Atomics) reactors, water is commonly used as a neutron moderator. A neutron moderator is a material that slows down fast neutrons, making them more likely to react with target materials for analysis. Water is an effective neutron moderator due to its high hydrogen content, which is efficient at slowing down neutrons via elastic scattering. This slowed-down neutron flux facilitates the activation of materials in NAA for subsequent analysis.

Q6. Radioactivity of a substance can be measured by

a.      TCD detector

b.      MCT detector

c.       EC detector

d.      Geiger Muller Counter

ANSWER:

d. Geiger Muller counter

EXPLANATION:

A Geiger Muller Counter is a device commonly used to measure radioactivity of substances. It detects ionizing radiation such as alpha, beta, and gamma radiation. When ionizing radiation interacts with the gas inside the counter, it produces a detectable electrical pulse, which is then counted and measured. Geiger Muller Counters are widely used in various applications, including radiation monitoring, laboratory research, and environmental protection.

Q7. In simple microscope if focal length of lens is 1 cm, then magnification power lies at

a.      25-26

b.      30-35

c.       40-45

d.      50-55

ANSWER:

a. 25-26

Q8. Which of the following cannot be used as a source of Infrared Radiation?

a.      Incandescent Lamp

b.      Nernst Glower

c.       Mercury Arc

d.      Tungsten Lamp

ANSWER:

c. mercury arc

EXPLANATION:

Mercury arc lamps primarily emit ultraviolet (UV) radiation rather than infrared. They are often used in applications such as ultraviolet curing, disinfection, and fluorescence microscopy.

Q9. Assertion (A): In HPLC, either isocratic or gradient elution may be used as a solvent system.

Reason (R): Isocratic solvent system improve a poor HPLC separation and a gradient solvent system has advantage of speed and simplicity.

Codes:

a.       Both (A) and (R) are correct.

b.      (A) is correct, but (R) is incorrect.

c.       Both (A) and (R) are incorrect.

d.      (A) is incorrect, but (R) is correct.

ANSWER:

a. Both A and R are correct

EXPLANATION:

In High-Performance Liquid Chromatography (HPLC), both isocratic and gradient elution can indeed be used as solvent systems. Isocratic elution involves the use of a constant mobile phase composition throughout the chromatographic run, while gradient elution involves changing the mobile phase composition over time. Both methods have their advantages and applications in HPLC analysis.

Isocratic elution is indeed useful for improving separations when dealing with compounds that have similar retention times, while gradient elution offers advantages in terms of speed and simplicity, especially for complex mixtures.

Q10. Following instrument can view a particle under a microscope while at the same time a beam of light is directed at the particle in order to obtain its absorption spectrum

a.  Atomic force microscope

b.  XRF spectrograph

c.  Micro spectrophotometer

d. XRD spectrograph

ANSWER:

c.  Micro spectrophotometer

EXPLANATION:

A micro spectrophotometer is an instrument used to measure the absorption spectrum of microscopic samples. It combines the functions of a microscope and a spectrophotometer, allowing researchers to view particles under a microscope while simultaneously directing a beam of light at the particle to obtain its absorption spectrum.

Atomic force microscopes (a) are used for imaging surfaces at the nanoscale and do not typically involve spectral analysis. XRF spectrographs (b) are used for elemental analysis through X-ray fluorescence, and they do not involve absorption spectra. XRD spectrographs (d) are used for determining the crystal structure of materials through X-ray diffraction, and they also do not involve absorption spectra.

Author:- Bhawana Sharma