Questions Set-2_Instrument Based Questions

INSTRUMENTATION

 

Q1. In a solid sample preparation technique in IR spectroscopy, the finely ground solid sample is mixed with mineral oil to make a thick paste which is then spread between IR transparent windows. What is the name of this solid sample preparation technique?

a.      Pressed pellet

b.      Mull technique

c.       Solid films

d.      Solid run in solutions

ANSWER:

b. Mull technique.

EXPLANATION:

The Mull technique is a solid sample preparation technique used in infrared (IR) spectroscopy. In this technique, a finely ground solid sample is mixed with a suitable mulling agent, often mineral oil, to form a thick paste. This paste is then spread evenly between two IR transparent windows, typically made of materials like sodium chloride (NaCl) or potassium bromide (KBr).

Once the paste is evenly distributed between the windows, pressure is applied to ensure good contact and uniformity. The resulting "mull" is then suitable for analysis using IR spectroscopy.

Q2. Which one of the following cannot be conserved during Raman Scattering?

a.      Total energy

b.      Momentum

c.       Kinetic energy

d.      Electronic energy

ANSWER:

  c.  Kinetic Energy

EXPLANATION:

Raman scattering is a phenomenon observed when light interacts with matter, resulting in a shift in energy due to the interaction with vibrational modes of the molecules.

Q3. Given below are two statements one is labelled as Assertion A and the other is labelled as Reason R

Assertion A: Water is a weak scatterer and therefore an excellent solvent for Raman work.

Reason R: This has important consequences in studies of biochemicals and pharmaceuticals.

In the light of the above statements, choose the most appropriate answer from the options given below

a.      Both A and R are true and R is the correct explanation of A.

b.      Both A and R are true but R is not the correct explanation of A.

c.       A is true but R is false.

d.      A is false but R is true.

ANSWER:

a.      Both A and R are true and R is the correct explanation of A.

EXPLANATION:

Water molecules have relatively few Raman-active modes compared to many other solvents or molecules, making water a weak scatterer in Raman spectroscopy. This characteristic is advantageous because it reduces interference from the solvent in Raman spectra, allowing for clearer identification and analysis of solute molecules.

By using water as a solvent, researchers can minimize background interference in Raman spectra, leading to more precise analysis and interpretation of the data. This is particularly important in fields such as biochemistry and pharmaceuticals, where small changes in molecular structure or composition can have significant implications for function and efficacy

 

Q4.  X Ray diffraction patterns are used for studying crystal structure of solids because

a.      They have very high energy; hence they can penetrate through solids.

b.      They are electromagnetic radiations and hence do not interact with crystals.

c.       Their wavelengths are comparable to inter-atomic distances.

d.      Their high frequency enables rapid analysis.

ANSWER:

c.           Their wavelengths are comparable to inter-atomic distances.

EXPLANATION:

The key reason for using X-rays in diffraction studies is that their wavelengths are comparable to the inter-atomic distances in crystals. This allows X-rays to interact with the atoms in the crystal lattice in a way that produces constructive and destructive interference patterns, which can be detected and analyzed to reveal information about the arrangement of atoms in the crystal.

Q5. In which one of the following types of liquid chromatography, immobilized biochemical is used as a stationary phase?

a.      Ion exchange chromatography

b.      Exclusion chromatography

c.       Affinity chromatography

d.      Gel permeation chromatography

ANSWER:

c. affinity chromatography

EXPLANATION:

In affinity chromatography, the stationary phase consists of a matrix to which a specific ligand is covalently attached. This ligand has a high affinity for the target molecule or biomolecule of interest. When the sample containing the target molecule is passed through the column, the target molecule binds selectively to the immobilized ligand while other molecules pass through or are washed away. This allows for highly specific purification of the target molecule based on its affinity for the immobilized biochemical.

Q6. Which of the following are advantages of solid-phase extraction over liquid extraction?

A.      Small sample size

B.      High solvent consumption

C.      Emulsion formation

D.     High extraction efficiency

Codes

a.      B and C only

b.      A and B only

c.       A and D only

d.      C and D only

ANSWER:

c.           A and D only

EXPLANATION:

Solid-phase extraction (SPE) offers several advantages over liquid extraction techniques:

A. Small sample size: SPE typically requires smaller sample sizes compared to liquid-liquid extraction. This is because solid-phase extraction often involves concentrating analytes onto a solid sorbent material, allowing for effective extraction of target compounds even from small sample volumes.

D. High extraction efficiency: Solid-phase extraction can achieve high extraction efficiency for target analytes. By selecting an appropriate sorbent material and optimizing the extraction conditions, SPE can effectively capture and concentrate analytes from complex sample matrices, leading to high extraction efficiency.

Q7. Match List I with List II

LIST I	LIST II
A.      Refractive Index	I.           3.1
B.      Inductively coupled plasma mass spectrometer	II.         An instrument used for both for glass digestion and elemental analysis for determination of the chemical composition
C.      Lead crystal glass density in (g/mL)	III.       1.467
D.     Refractive index of olive oil	IV.       Becke line

 

Codes

a.      A- I, B-III, C-II, D-IV

b.      A-IV, B-II, C-I, D-III

c.       A-III, B- II, C-I, D-IV

d.      A-I, B -IV, C- III, D-II

ANSWER:

b.           A-IV, B-II, C-I, D-III

Q8. The system for measurement of ion intensity in the GC-MS system consists of which one of the following?

a.      Band pass amplifier

b.      Narrow band amplifier

c.       Wide band amplifier

d.      Low pass amplifier

ANSWER:

c. Wide band amplifier.

EXPLANATION:

In a GC-MS system, the ion intensity is measured by the mass spectrometer component. After ionization of analyte molecules in the gas chromatograph, the ions are subjected to mass analysis in the mass spectrometer.

The system for measuring ion intensity typically involves amplifiers to boost the signal generated by the ions. Since the ion signals produced by the mass spectrometer cover a range of frequencies (corresponding to different masses of ions), a wide band amplifier is required to capture and amplify these signals effectively

Q9. Which one of the following statements is NOT true about mass spectroscopy?

a.       Impurities of masses different from the one being analysed interfere with the result.

b.      It has great sensitivity

c.       It is suitable for data storage

d.      It is suitable for library retrieval

ANSWER:

a.       Impurities of masses different from the one being analysed interfere with the result.

EXPLANATION:

Mass spectrometry is primarily used for the analysis of samples and the generation of mass spectra, which provide information about the masses and abundances of ions in the sample.

Q10. Which of the following is NOT a limitation of Beer Lambert’s Law, which gives the relation between absorption, thickness and concentration?

a.       Concentration must be lower

b.      Radiation must have higher bandwidth

c.       Radiation source must be monochromatic

d.      Does not consider factors other than thickness and concentration

ANSWER:

b. Radiation must have higher bandwidth.

EXPLANATION:

b. Radiation must have higher bandwidth: Not a limitation. Beer-Lambert's Law does not require the radiation to have a higher bandwidth. In fact, it often assumes monochromatic radiation.

 

Author:- Bhawana Sharma