Objective questions (MCQ) on Laboratory Techniques and Instrumentation for ICAR-JRF/SRF/CSIR/GATE Exams

1. Which of the following is the most appropriate glassware for accurately measuring a specific volume of liquid for a titration? (a) Beaker (b) Erlenmeyer flask (c) Graduated cylinder (d) Volumetric pipette
2. When using a micropipette, the second stop on the plunger is primarily used for: (a) Setting the volume (b) Dispensing the remaining liquid after the first stop (c) Ejecting the tip (d) Pre-wetting the tip
3. Which of the following techniques is best suited for separating a solid precipitate from a liquid? (a) Distillation (b) Evaporation (c) Filtration (d) Chromatography
4. The purpose of “taring” a balance before weighing a sample is to: (a) Ensure the balance is level (b) Calibrate the balance with a known weight (c) Set the balance reading to zero with a container on it (d) Protect the balance pan from contamination
5. In spectrophotometry, the Beer-Lambert Law relates absorbance to: (a) Wavelength and frequency (b) Path length and concentration (c) Intensity of incident and transmitted light (d) Quantum yield and fluorescence
6. Which of the following is a common application of gas chromatography (GC)? (a) Separating proteins based on size (b) Identifying and quantifying volatile organic compounds (c) Determining the molecular weight of a polymer (d) Analyzing the elemental composition of a solid
7. The principle of separation in gel electrophoresis is based on the differential migration of molecules through a gel matrix under an electric field, primarily due to differences in: (a) Charge only (b) Size only (c) Charge and size (d) Hydrophobicity
8. Which of the following is a key component of a high-performance liquid chromatography (HPLC) system? (a) Vacuum pump (b) Flame ionization detector (c) High-pressure pump (d) Electron multiplier tube
9. In microscopy, the resolving power refers to the ability to: (a) Magnify an image (b) Distinguish between two closely spaced objects (c) Increase the brightness of the image (d) Focus on different planes of the specimen
10. Which type of microscopy is best suited for visualizing the surface topography of a sample at a very high magnification? (a) Bright-field microscopy (b) Phase-contrast microscopy (c) Scanning electron microscopy (SEM) (d) Transmission electron microscopy (TEM)
11. When performing a serial dilution, each step typically involves: (a) Adding more solute to the solution (b) Increasing the total volume of the solution without changing the solute amount (c) Transferring a fixed volume of the solution to a new tube and diluting it with solvent (d) Evaporating some of the solvent to increase the concentration
12. Which of the following is a common method for sterilizing heat-labile solutions? (a) Autoclaving (b) Dry heat sterilization (c) Filtration through a sterile membrane filter (d) Incineration
13. The purpose of a fume hood in a laboratory is primarily to: (a) Provide a sterile environment for experiments (b) Illuminate the work area (c) Protect the user from hazardous vapors (d) Regulate the temperature of experiments
14. In centrifugation, the rate at which particles sediment depends on their: (a) Density only (b) Size only (c) Shape only (d) Density, size, and shape
15. Which of the following is commonly used to visualize DNA fragments after gel electrophoresis? (a) Coomassie blue (b) Silver stain (c) Ethidium bromide (d) Bradford reagent
16. The principle behind atomic absorption spectroscopy (AAS) is the measurement of: (a) Light emitted by excited atoms (b) Light absorbed by ground-state atoms (c) The mass-to-charge ratio of ions (d) The scattering of light by atoms
17. Which of the following is a common detector used in UV-Vis spectrophotometry? (a) Flame ionization detector (FID) (b) Thermal conductivity detector (TCD) (c) Photodiode array (PDA) detector (d) Electron capture detector (ECD)
18. In polymerase chain reaction (PCR), the annealing step involves: (a) Denaturing the DNA double helix at a high temperature (b) Binding of primers to the single-stranded DNA templates at a specific temperature (c) Extending the DNA strands by a DNA polymerase at an optimal temperature (d) Cooling the reaction mixture to stop the reaction
19. Which of the following is a common method for determining the concentration of a protein in solution? (a) Titration with a standard acid (b) Spectrophotometry using a colorimetric assay (e.g., Bradford) (c) Gas chromatography-mass spectrometry (GC-MS) (d) Nuclear magnetic resonance (NMR) spectroscopy
20. In cell culture, maintaining sterility is crucial to prevent contamination by: (a) Carbon dioxide (b) Oxygen (c) Microorganisms (d) Nitrogen
21. Which of the following is the SI unit of volume commonly used in laboratory settings? (a) Liter (L) (b) Milliliter (mL) (c) Cubic meter (m3) (d) Microliter (μL)
22. When preparing a solution with a specific molarity, it is essential to use a: (a) Graduated cylinder to measure the solute (b) Beaker to dissolve the solute (c) Volumetric flask to make up the final volume (d) Erlenmeyer flask for mixing
23. Which of the following is a technique used for separating molecules based on their binding affinity to a stationary phase? (a) Distillation (b) Electrophoresis (c) Chromatography (d) Centrifugation
24. The accuracy of a measurement refers to: (a) How close repeated measurements are to each other (b) How close a measurement is to the true value (c) The number of significant figures in the measurement (d) The precision of the instrument used
25. In mass spectrometry, ions are separated based on their: (a) Mass only (b) Charge only (c) Mass-to-charge ratio (d) Velocity
26. Which of the following detectors is commonly used in gas chromatography for the analysis of non-organic gases? (a) Flame ionization detector (FID) (b) Electron capture detector (ECD) (c) Thermal conductivity detector (TCD) (d) Nitrogen phosphorus detector (NPD)
27. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), SDS is used to: (a) Denature proteins and give them a uniform negative charge (b) Stabilize the gel matrix (c) Enhance the staining of proteins (d) Increase the pore size of the gel
28. Which of the following is a common stationary phase used in HPLC? (a) Helium gas (b) A packed column with silica-based particles (c) A capillary column coated with a polymer (d) An electric field
29. The numerical aperture (NA) of a microscope objective lens is a measure of its ability to: (a) Magnify the specimen (b) Gather light and resolve fine detail (c) Increase the working distance (d) Enhance the contrast of the image
30. Which microscopy technique is used to visualize live cells and their internal structures without staining? (a) Fluorescence microscopy (b) Confocal microscopy (c) Phase-contrast microscopy (d) Bright-field microscopy
31. When preparing a dilution, the dilution factor is the ratio of the: (a) Volume of solute to the total volume of the solution (b) Initial concentration to the final concentration (c) Final volume to the initial volume (d) Amount of solute to the amount of solvent
32. Autoclaving typically uses which combination of conditions for sterilization? (a) High temperature and dry heat (b) High pressure and steam (c) UV radiation and filtration (d) Chemical disinfectants and low temperature
33. A biological safety cabinet (BSC) is designed to protect: (a) Only the sample from contamination (b) Only the user from biohazards (c) The sample, the user, and the environment from biohazards (d) Only the environment from biohazards
34. In differential centrifugation, cellular components are separated based on differences in their: (a) Charge-to-mass ratio (b) Solubility (c) Sedimentation rate (d) Binding affinity
35. Which stain is commonly used for general protein visualization in SDS-PAGE gels? (a) Ethidium bromide (b) Coomassie blue (c) Silver stain (d) Crystal violet
36. In atomic emission spectroscopy (AES), the intensity of emitted light is proportional to the: (a) Concentration of the element in the sample (b) Wavelength of the emitted light (c) Energy of the incident radiation (d) Mass of the sample
37. Which type of spectrophotometer uses two light beams to compensate for fluctuations in the light source and detector? (a) Single-beam spectrophotometer (b) Double-beam spectrophotometer (c) Atomic absorption spectrophotometer (d) Fluorescence spectrophotometer
38. The extension step in PCR involves: (a) Separation of DNA strands (b) Binding of primers (c) DNA synthesis by polymerase (d) Cooling to stop the reaction
39. The Bradford assay for protein quantification relies on the binding of a dye to proteins, causing a shift in the dye’s: (a) Fluorescence (b) Absorbance spectrum (c) Refractive index (d) Conductivity
40. Laminar flow hoods are used in cell culture to: (a) Provide a high concentration of carbon dioxide (b) Maintain a sterile work environment (c) Regulate the temperature of the incubator (d) Control the humidity levels
41. The unit “ppm” (parts per million) typically refers to: (a) Grams of solute per liter of solution (b) Milligrams of solute per kilogram of solution (c) Moles of solute per liter of solution (d) Percentage by volume
42. To prepare a solution with a specific percentage by weight (% w/w), you would need to know the: (a) Molar mass of the solute (b) Density of the solvent (c) Mass of the solute and the total mass of the solution (d) Volume of the solute and the volume of the solvent
43. Which of the following chromatographic techniques is often used for separating volatile compounds? (a) Ion exchange chromatography (b) Size exclusion chromatography (c) Gas chromatography (d) Affinity chromatography
44. Precision in measurements refers to: (a) How close a measurement is to the true value (b) The smallest unit that can be measured by an instrument (c) The reproducibility of the measurements (d) The accuracy of the instrument
45. In tandem mass spectrometry (MS/MS), the primary advantage is the ability to: (a) Increase the sensitivity of detection (b) Determine the elemental composition more accurately (c) Obtain structural information about the analyte (d) Separate isomers more effectively
46. A flame ionization detector (FID) in gas chromatography is particularly sensitive to: (a) Halogenated compounds (b) Compounds containing nitrogen and phosphorus (c) Hydrocarbons (d) Inorganic gases
47. In isoelectric focusing (IEF), proteins are separated based on their: (a) Size (b) Charge at a specific pH (c) Isoelectric point (pI) (d) Binding affinity
48. Which of the following is a common mobile phase used in reversed-phase HPLC? (a) A polar solvent (e.g., water, methanol mixture) (b) A nonpolar solvent (e.g., hexane) (c) An electric field (d) A gas (e.g., helium)
49. The working distance of a microscope objective is the distance between the: (a) Objective lens and the eyepiece (b) Objective lens and the specimen when in focus (c) Light source and the specimen (d) Eyepiece and the observer’s eye
50. Fluorescence microscopy is particularly useful for visualizing: (a) The ultrastructure of organelles (b) Specific molecules or structures within cells using fluorescent probes (c) The surface of opaque samples (d) Unstained live cells
51. To prepare a 1:5 dilution of a stock solution, you would mix: (a) 1 part stock solution with 4 parts solvent (b) 1 part stock solution with 5 parts solvent (c) 5 parts stock solution with 1 part solvent (d) 5 parts stock solution with 4 parts solvent
52. Pasteurization is a method of sterilization that primarily aims to: (a) Kill all microorganisms (b) Reduce the number of viable microorganisms (c) Remove particulate matter (d) Inactivate viruses
53. When working with potentially infectious biological samples, it is essential to use: (a) A standard laboratory coat (b) A fume hood (c) A biological safety cabinet (d) A chemical spill kit
54. Ultracentrifugation is used for separating: (a) Small molecules based on size (b) Proteins based on charge (c) Macromolecules and organelles based on sedimentation rate (d) Volatile compounds based on boiling point
55. Silver staining of protein gels is more sensitive than Coomassie blue staining because it: (a) Binds more strongly to proteins (b) Reacts chemically with proteins to deposit silver (c) Changes the pH of the gel (d) Requires a shorter staining time
56. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) typically introduces the sample as a(n): (a) Solid (b) Gas (c) Plasma (d) Liquid
57. A nephelometer measures the: (a) Absorbance of a solution (b) Emission of light from a sample (c) Scattering of light by particles in a suspension (d) Refraction of light through a sample
58. In quantitative PCR (qPCR), the amount of PCR product is measured: (a) Only at the end of the reaction (b) In real-time during the reaction (c) After gel electrophoresis (d) By the size of the amplified fragment
59. Enzyme-linked immunosorbent assay (ELISA) is a technique used for: (a) Separating DNA fragments (b) Detecting and quantifying a specific substance (e.g., protein, antibody) (c) Amplifying DNA sequences (d) Analyzing the elemental composition of a sample
60. An incubator used for cell culture typically controls: (a) Temperature only (b) Humidity only (c) Temperature, humidity, and CO2 levels (d) Light intensity and pH
61. The term “aliquot” refers to a: (a) Stock solution of high concentration (b) Small, measured portion of a sample or solution (c) Container used for storing chemicals (d) Procedure for calibrating an instrument
62. When preparing a solution, it is important to ensure that the solute is completely: (a) Filtered (b) Evaporated (c) Dissolved (d) Centrifuged
63. Size exclusion chromatography separates molecules based on their: (a) Charge (b) Hydrophobicity (c) Size and shape (d) Binding affinity
64. The term “blank” in spectrophotometry refers to a sample that: (a) Contains the analyte at a known concentration (b) Contains only the solvent and other reagents but not the analyte (c) Has an absorbance of zero at all wavelengths (d) Is used to calibrate the instrument after each measurement
65. In inductively coupled plasma mass spectrometry (ICP-MS), the sample is introduced as an aerosol into: (a) A flame (b) A graphite furnace (c) An argon plasma (d) A vacuum chamber
66. A thermal conductivity detector (TCD) in gas chromatography detects changes in the: (a) Electrical conductivity of the eluent (b) Temperature of a filament caused by the eluent’s thermal conductivity (c) Ionization of the eluent in a flame (d) Absorption of UV light by the eluent
67. Two-dimensional gel electrophoresis separates proteins based on their: (a) Size in both dimensions (b) Charge in both dimensions (c) Isoelectric point in one dimension and size in the other (d) Hydrophobicity in one dimension and size in the other
68. In HPLC, the retention time of a analyte is the time it takes for it to: (a) Pass through the detector (b) Elute from the column after injection (c) Reach the stationary phase (d) Be injected into the system

69. The objective lens of a microscope that should be used first to locate the specimen is usually the: (a) Highest magnification objective (b) Lowest magnification objective (c) Oil immersion objective (d) Objective with the smallest numerical aperture
70. Confocal microscopy improves resolution compared to standard fluorescence microscopy by: (a) Using multiple excitation wavelengths (b) Detecting fluorescence from the entire sample volume (c) Excluding out-of-focus light with a pinhole aperture (d) Using a more powerful light source
71. A stock solution is a: (a) Diluted solution ready for immediate use (b) Concentrated solution that will be diluted to a lower concentration for use (c) Solution with an unknown concentration (d) Solid reagent that needs to be dissolved
72. When diluting an acid, it is always important to add: (a) Water to the acid quickly (b) Acid to water slowly and with stirring (c) The acid and water simultaneously (d) Water to the acid slowly
73. Ion exchange chromatography separates molecules based on their: (a) Size (b) Charge (c) Hydrophobicity (d) Binding affinity
74. The wavelength at which a substance absorbs the most light in spectrophotometry is called the: (a) Transmittance maximum (b) Absorbance minimum (c) Lambda max (λmax​) (d) Isosbestic point
75. Graphite furnace atomic absorption spectroscopy (GFAAS) generally offers: (a) Lower sensitivity than flame AAS (b) Higher sensitivity than flame AAS (c) Similar sensitivity to flame AAS but faster analysis times (d) The ability to analyze only gaseous samples
76. An electron capture detector (ECD) in gas chromatography is highly sensitive to compounds containing: (a) Carbon and hydrogen only (b) Nitrogen and phosphorus (c) Halogens (d) Oxygen
77. Western blotting is a technique used to detect: (a) Specific DNA sequences (b) Specific RNA sequences (c) Specific proteins (d) Specific lipids
78. In reversed-phase HPLC, the stationary phase is typically: (a) Polar (b) Nonpolar (c) Charged (d) Hydrophilic
79. The total magnification of a compound light microscope is calculated by: (a) Adding the magnification of the objective lens and the eyepiece (b) Multiplying the magnification of the objective lens and the eyepiece (c) Subtracting the magnification of the eyepiece from the objective lens (d) Dividing the magnification of the objective lens by the eyepiece
80. Which type of microscopy is often used to visualize the three-dimensional structure of cells and tissues using optical sectioning? (a) Transmission electron microscopy (b) Scanning electron microscopy (c) Confocal microscopy (d) Atomic force microscopy
81. To make 100 mL of a 0.5 M solution from a 1 M stock solution, you would need: (a) 25 mL of stock solution (b) 50 mL of stock solution (c) 75 mL of stock solution (d) 10 mL of stock solution
82. Dry heat sterilization is typically used for: (a) Culture media (b) Surgical instruments that can withstand high temperatures (c) Solutions that cannot be autoclaved (d) Biological samples
83. A chemical spill in the laboratory should be: (a) Ignored if it is small (b) Cleaned up immediately using appropriate procedures and safety equipment (c) Reported at the end of the day (d) Neutralized with a universal neutralizer regardless of the chemical
84. The Svedberg unit (S) is a measure of a particle’s: (a) Molecular weight (b) Density (c) Sedimentation rate during centrifugation (d) Charge-to-mass ratio
85. The Bradford reagent changes color upon binding to proteins, shifting from: (a) Yellow to blue (b) Blue to yellow (c) Colorless to purple (d) Purple to colorless
86. Which of the following is a common application of inductively coupled plasma mass spectrometry (ICP-MS)? (a) Identification of organic molecules (b) Elemental analysis of various sample types (c) Determination of protein structure (d) Separation of volatile compounds
87. A turbidimeter measures the: (a) Light absorbed by a solution (b) Light emitted by a sample (c) Reduction in light intensity as it passes through a suspension (d) Refractive index of a liquid
88. Reverse transcription PCR (RT-PCR) is used to: (a) Amplify DNA from an RNA template (b) Quantify the amount of DNA in a sample (c) Detect specific proteins (d) Separate RNA molecules by size
89. Immunofluorescence is a technique that uses: (a) Radioactive isotopes to label molecules (b) Fluorescently labeled antibodies to detect specific antigens (c) Enzymes to amplify signals (d) Heavy metals to enhance contrast in electron microscopy
90. A Coulter counter is used for: (a) Measuring the size and number of cells (b) Separating cells based on density (c) Imaging the internal structures of cells (d) Analyzing the DNA content of cells
91. The term “supernatant” refers to the: (a) Solid pellet collected at the bottom of a centrifuge tube (b) Liquid remaining above the pellet after centrifugation (c) Layer between two immiscible liquids (d) Foam that forms on top of a vigorously mixed solution
92. When weighing a hygroscopic substance, it is best to: (a) Leave it exposed to the air for a few minutes before weighing (b) Weigh it in a closed container (c) Use a rough balance to get an approximate weight (d) Heat it gently before weighing
93. Affinity chromatography separates molecules based on: (a) Size (b) Charge (c) Specific binding interactions (d) Hydrophobicity
94. The purpose of a monochromator in a spectrophotometer is to: (a) Focus the light beam onto the sample (b) Detect the light that passes through the sample (c) Select a specific wavelength of light (d) Increase the intensity of the light source
95. Which of the following is a common ionization technique used in mass spectrometry for large biomolecules like proteins? (a) Electron ionization (EI) (b) Chemical ionization (CI) (c) Electrospray ionization (ESI) (d) Atmospheric pressure chemical ionization (APCI)
96. A nitrogen phosphorus detector (NPD) in gas chromatography is selectively sensitive to compounds containing: (a) Halogens (b) Sulfur (c) Nitrogen and phosphorus (d) Carbonyl groups
97. Southern blotting is a technique used to detect: (a) Specific proteins (b) Specific RNA sequences (c) Specific DNA sequences (d) Specific lipids
98. In normal-phase HPLC, the stationary phase is: (a) Nonpolar (b) Polar (c) Charged (d) Hydrophobic
99. The resolution of a microscope is defined as the: (a) Ability to magnify an image (b) Smallest distance between two points that can be distinguished (c) Brightness of the image (d) Range of wavelengths that can be used for imaging
100. Atomic force microscopy (AFM) is used to image surfaces by: (a) Scanning a focused beam of electrons (b) Measuring the force between a sharp tip and the surface (c) Detecting transmitted light through the sample (d) Using fluorescent probes
101. To prepare 500 mL of a 100 ppm solution from a 1000 ppm stock solution, you would need: (a) 5 mL of stock solution (b) 50 mL of stock solution (c) 10 mL of stock solution (d) 100 mL of stock solution
102. Filtration sterilization is effective for removing: (a) Viruses (b) Small proteins (c) Bacteria and other microorganisms (d) Dissolved chemicals
103. When working under a laminar flow hood, it is important to: (a) Block the airflow with your hands frequently (b) Work quickly to minimize exposure (c) Maintain a clean work area and avoid disrupting the airflow (d) Turn off the airflow when making minor adjustments
104. Rate zonal centrifugation separates particles based on: (a) Density only (b) Size only (c) Density and size, with separation primarily due to size (d) Charge
105. Coomassie blue stain binds to proteins primarily through: (a) Covalent bonds (b) Ionic and hydrophobic interactions (c) Hydrogen bonds (d) Van der Waals forces
106. X-ray fluorescence (XRF) spectroscopy is used for: (a) Determining the molecular structure of crystals (b) Elemental analysis by detecting emitted X-rays (c) Imaging the surface of materials at nanoscale (d) Measuring the absorbance of solutions in the UV-Vis range
107. A refractometer measures the: (a) Bending of light as it passes through a substance (b) Amount of light scattered by a solution (c) Light emitted by an excited sample (d) Light absorbed by a sample at different wavelengths
108. Nucleic acid amplification techniques other than PCR include: (a) Western blotting (b) ELISA (c) Loop-mediated isothermal amplification (LAMP) (d) Flow cytometry
109. Immunohistochemistry (IHC) is a technique used to: (a) Amplify DNA in tissue samples (b) Detect specific proteins in tissue sections using antibodies (c) Visualize RNA localization within cells (d) Analyze the elemental composition of tissues
110. Flow cytometry allows for the analysis of: (a) The sequence of DNA in a cell (b) The proteins present on the surface of a cell (c) Physical and chemical characteristics of a population of cells (d) The metabolic activity of a single cell
111. A meniscus is the: (a) Curved upper surface of a liquid in a container (b) Solid that precipitates out of a solution (c) Point at which a titration is complete (d) Smallest volume that can be measured by a graduated cylinder
112. When using a volumetric flask, the final volume of the solution should be adjusted so that the meniscus of the liquid is: (a) Above the calibration mark (b) Below the calibration mark (c) Exactly on the calibration mark (d) Slightly above or below depending on the liquid
113. Hydrophobic interaction chromatography separates proteins based on their: (a) Size (b) Charge (c) Tendency to interact with hydrophobic surfaces (d) Binding to specific ligands
114. The Beer-Lambert Law can be expressed as A = $\epsilon$bc, where ϵ represents the: (a) Absorbance (b) Path length (c) Concentration (d) Molar absorptivity
115. Secondary ion mass spectrometry (SIMS) analyzes a sample by: (a) Bombarding it with electrons (b) Bombarding it with ions and detecting the emitted secondary ions (c) Heating it in a furnace (d) Passing X-rays through it
116. A flame photometric detector (FPD) in gas chromatography is specifically used for detecting compounds containing: (a) Carbon and hydrogen (b) Nitrogen and phosphorus (c) Sulfur and phosphorus (d) Halogens
117. Northern blotting is a technique used to detect: (a) DNA (b) RNA (c) Proteins (d) Lipids
118. In size exclusion chromatography, larger molecules elute: (a) Earlier than smaller molecules (b) Later than smaller molecules (c) At the same time as smaller molecules (d) Depends on the flow rate
119. The eyepiece of a microscope typically has a magnification of: (a) 4x (b) 10x (c) 40x (d) 100x
120. Scanning tunneling microscopy (STM) is used to image conductive surfaces at the atomic level by measuring: (a) The deflection of a cantilever (b) The current between a sharp tip and the surface (c) Emitted electrons (d) Transmitted light
121. A serial dilution involves multiple steps of: (a) Increasing the concentration (b) Decreasing the volume (c) Diluting a sample by the same factor repeatedly (d) Adding different solutes
122. Ethylene oxide sterilization is typically used for: (a) Heat-stable liquids (b) Moisture-sensitive materials (c) Biological safety cabinets (d) Large metal instruments
123. When using a biological safety cabinet, the work should be performed: (a) Near the front opening (b) At the back of the cabinet (c) In the middle of the work area (d) Outside the cabinet to avoid contamination
124. Density gradient centrifugation separates particles based on their: (a) Size (b) Shape (c) Buoyant density (d) Charge
125. Silver staining of gels visualizes proteins by: (a) Binding directly to peptide bonds (b) Reducing silver ions to metallic silver on the protein bands (c) Fluorescing under UV light when bound to proteins (d) Changing the pH around the protein bands
126. Nuclear magnetic resonance (NMR) spectroscopy is primarily used to determine the: (a) Elemental composition of a sample (b) Structure and dynamics of molecules (c) Concentration of ions in solution (d) Thermal properties of materials
127. A flame photometer measures the intensity of light emitted by elements that have been: (a) Excited by UV radiation (b) Passed through a magnetic field (c) Introduced into a flame (d) Bombarded with electrons
128. Branched DNA (bDNA) assay is a method for: (a) Amplifying DNA (b) Detecting and quantifying RNA or DNA without amplification (c) Sequencing DNA (d) Separating DNA fragments
129. Enzyme-linked immunosorbent spot (ELISpot) assay is used to: (a) Detect the presence of a specific protein in a solution (b) Determine the number of cells secreting a specific molecule (c) Amplify DNA from single cells (d) Analyze the surface markers of cells
130. Impedance flow cytometry measures changes in: (a) Light scattering of cells (b) Electrical resistance as cells pass through a small aperture (c) Fluorescence emitted by labeled cells (d) The size of cells using laser diffraction
131. A volumetric pipette is designed to deliver: (a) Variable volumes of liquid (b) A single, precise volume of liquid (c) Small volumes with high accuracy (d) Volumes based on graduations
132. When reading the volume of a liquid in a graduated cylinder, your eye level should be: (a) Above the meniscus (b) Below the meniscus (c) At the level of the meniscus (d) Doesn’t matter as long as you are consistent
133. Gel filtration chromatography is another term for: (a) Ion exchange chromatography (b) Affinity chromatography (c) Size exclusion chromatography (d) Hydrophobic interaction chromatography
134. The molar absorptivity (ϵ) in the Beer-Lambert Law is: (a) Dependent on the concentration of the analyte (b) Dependent on the path length of the light beam (c) A constant specific to the analyte at a given wavelength (d) Unitless
135. Time-of-flight (TOF) mass analyzers separate ions based on their: (a) Mass-to-charge ratio and velocity (b) Time it takes for them to travel a fixed distance (c) Stability in a magnetic field (d) Ability to be deflected by an electric field
136. A pulsed flame photometric detector (PFPD) in gas chromatography can provide information about: (a) Only sulfur-containing compounds (b) Only phosphorus-containing compounds (c) Both sulfur and phosphorus compounds, with element-specific responses (d) Hydrocarbons with high sensitivity
137. Dot blot is a technique similar to Western blotting but differs in that: (a) Proteins are separated by electrophoresis before transfer (b) RNA is the target molecule (c) DNA is the target molecule (d) The sample is directly spotted onto the membrane without prior separation
138. In ion exchange chromatography, a cation exchange resin would bind to molecules that are: (a) Negatively charged (b) Positively charged (c) Hydrophobic (d) Large in size

139. The objective lens of a microscope that provides the highest magnification is typically the: (a) Scanning power objective (b) Low power objective (c) High power objective (d) Oil immersion objective
140. Super-resolution microscopy techniques overcome the diffraction limit of light, allowing for the visualization of structures smaller than about: (a) 1 micrometer (b) 200 nanometers (c) 10 nanometers (d) 1 nanometer
141. When preparing a percentage solution (e.g., % w/v), it is important to: (a) Add solute to the final volume of solvent (b) Make up to the final volume with the solvent after adding the solute (c) Measure both solute and solvent by weight (d) Ensure the temperature is exactly 25°C
142. Ultraviolet (UV) sterilization is most effective against: (a) Bacterial spores (b) Viruses (c) Vegetative bacteria and fungi (d) Prions
143. A Class III biological safety cabinet provides the highest level of protection because it is: (a) Open to the laboratory environment (b) Ventilated with non-recirculated air (c) Gas-tight and requires the use of gloves attached to the cabinet (d) Equipped with only one HEPA filter
144. The sedimentation coefficient (s) of a particle is affected by: (a) Only the viscosity of the medium (b) Only the centrifugal force applied (c) The particle’s mass, density, and the viscosity of the medium (d) Only the rotor speed
145. In gel electrophoresis, a tracking dye (e.g., bromophenol blue) is used to: (a) Stain the nucleic acids or proteins (b) Visualize the migration of the molecules and indicate when to stop the electrophoresis (c) Increase the conductivity of the buffer (d) Prevent the samples from diffusing out of the wells
146. Fourier transform infrared (FTIR) spectroscopy is used to identify substances based on their: (a) Absorption of ultraviolet light (b) Emission of light when excited (c) Absorption of infrared radiation causing molecular vibrations (d) Scattering of X-rays
147. A chemiluminescence detector measures light emitted from: (a) A sample heated to a high temperature (b) A chemical reaction that produces light (c) A fluorescent substance excited by UV light (d) A radioactive decay process
148. Nucleic acid sequencing techniques include: (a) ELISA and Western blotting (b) Sanger sequencing and next-generation sequencing (NGS) (c) PCR and RT-PCR (d) Southern and Northern blotting
149. Flow cytometry can quantify: (a) The sequence of a specific gene (b) The amount of a specific protein expressed by a cell (c) The three-dimensional structure of a protein (d) The metabolic pathways active in a cell
150. A hemocytometer is used to: (a) Measure the size of red blood cells (b) Count cells in a known volume of liquid (c) Determine the hemoglobin concentration in blood (d) Separate different types of blood cells
151. A burette is primarily used for: (a) Measuring precise volumes of liquids to be transferred at once (b) Delivering variable, precise volumes of liquid, especially in titrations (c) Storing solutions (d) Mixing solutions vigorously
152. Parallax error occurs when reading a graduated cylinder if: (a) The cylinder is not perfectly vertical (b) The liquid is highly viscous (c) Your eye is not at the same horizontal level as the meniscus (d) The cylinder is dirty
153. Lectin affinity chromatography is used to separate glycoproteins based on their binding to: (a) Metal ions (b) Nucleic acids (c) Carbohydrates (d) Antibodies
154. The isoelectric point (pI) of a protein is the pH at which the protein has: (a) A net positive charge (b) A net negative charge (c) No net electrical charge (d) Maximum solubility
155. Matrix-assisted laser desorption/ionization (MALDI) is an ionization technique used in mass spectrometry primarily for: (a) Small, volatile organic molecules (b) Large biomolecules like peptides and proteins (c) Elemental analysis of solids (d) Isotope ratio measurements
156. A Hall electrolytic conductivity detector (HECD) in gas chromatography is selective for compounds containing: (a) Hydrocarbons (b) Halogens, sulfur, and nitrogen (c) Phosphorus (d) Oxygen
157. Far-Western blotting is used to study: (a) DNA-DNA interactions (b) RNA-protein interactions (c) Protein-protein interactions (d) DNA-protein interactions
158. In reversed-phase chromatography, analytes with higher hydrophobicity tend to elute: (a) Earlier (b) Later (c) At the same time as hydrophilic analytes (d) Depends on the flow rate
159. The oil immersion objective lens on a microscope is used to: (a) Increase the depth of field (b) Achieve the highest magnification and resolution (c) View unstained specimens (d) Decrease the working distance
160. Scanning probe microscopy techniques, such as AFM and STM, typically use a sharp tip to: (a) Transmit electrons through the sample (b) Detect scattered light from the sample (c) Interact mechanically or electronically with the sample surface (d) Emit fluorescent light
161. When making a dilution, the formula M1​V1​=M2​V2​ is used to calculate the required volume of the stock solution, where M represents: (a) Mass (b) Molarity (c) Molality (d) Mole fraction
162. Gamma irradiation is a method of sterilization commonly used for: (a) Heat-labile solutions (b) Medical devices and plastics (c) Culture media components (d) Laboratory air
163. The airflow in a Class II biological safety cabinet is: (a) Unidirectional, flowing outward from the cabinet (b) Recirculated within the cabinet without HEPA filtration (c) Inward through the front opening, downward over the work surface, and exhausted or recirculated through HEPA filters (d) Only exhausted to the outside
164. The buoyant force on a particle during centrifugation depends on the density of the: (a) Particle (b) Solvent (c) Centrifuge rotor (d) Sample container
165. In capillary electrophoresis (CE), separation of molecules occurs based on their: (a) Size and shape only (b) Charge-to-size ratio (c) Hydrophobicity (d) Binding affinity
166. Raman spectroscopy provides information about a molecule’s: (a) Electronic transitions (b) Vibrational and rotational modes (c) Nuclear spin states (d) Mass-to-charge ratio
167. A pulsed discharge helium ionization detector (PDHID) in gas chromatography is known for its: (a) Specificity to halogenated compounds (b) Universal response to almost all organic and inorganic compounds (c) High sensitivity to nitrogen-containing compounds (d) Ability to detect only non-combustible gases
168. Southwestern blotting is used to identify: (a) RNA-binding proteins (b) DNA-binding proteins (c) Protein-protein interactions (d) Lipid-binding proteins
169. In size exclusion chromatography, the stationary phase consists of: (a) Charged beads (b) Porous beads with a range of pore sizes (c) A hydrophobic matrix (d) Ligands specific to the target molecules
170. The numerical aperture (NA) of a microscope condenser affects the: (a) Magnification of the image (b) Resolution and brightness of the illumination (c) Working distance (d) Depth of field
171. To prepare a solution with a specific molality, you need to know the moles of solute and the: (a) Total volume of the solution (b) Mass of the solvent (c) Total mass of the solution (d) Density of the solution
172. Tyndallization is a sterilization method that involves: (a) Continuous heating at a high temperature (b) Intermittent heating to kill vegetative cells while allowing spores to germinate (c) Exposure to UV light for an extended period (d) Filtration through a very fine pore size membrane
173. When working with hazardous chemicals, a Safety Data Sheet (SDS) provides information on: (a) The cost of the chemical (b) The manufacturer’s contact information only (c) The properties, hazards, and handling of the chemical (d) Suggested experimental protocols
174. The relative centrifugal force (RCF) in centrifugation is proportional to: (a) The mass of the rotor (b) The speed of rotation squared and the radius (c) The viscosity of the sample (d) The density of the particles
175. Isoelectric focusing (IEF) is typically performed in a: (a) Polyacrylamide gel with a pH gradient (b) Agarose gel with an electric field (c) Capillary tube with a buffer solution (d) Chromatographic column
176. Energy-dispersive X-ray spectroscopy (EDS) is often used in conjunction with SEM to: (a) Increase the magnification (b) Determine the elemental composition of a small area (c) Enhance the surface contrast (d) Measure the sample’s conductivity
177. A mass flow controller (MFC) is used in gas chromatography to: (a) Regulate the temperature of the column (b) Control the flow rate of the carrier gas (c) Inject the sample onto the column (d) Detect the eluted compounds
178. Quantitative real-time PCR (qRT-PCR) allows for the determination of: (a) The size of the PCR product (b) The sequence of the amplified DNA (c) The initial amount of the template nucleic acid (d) The melting temperature of the DNA duplex
179. Flow cytometry can sort cells based on their: (a) DNA sequence (b) Size and internal complexity, as well as fluorescence (c) Metabolic activity (d) Ability to adhere to a surface
180. A Neubauer chamber is a type of: (a) Spectrophotometer (b) Cell counting slide (c) Centrifuge rotor (d) Chromatography column
181. A Pasteur pipette is typically used for: (a) Measuring precise volumes (b) Transferring small volumes of liquids dropwise (c) Performing titrations (d) Heating solutions uniformly
182. The term “tare weight” refers to the weight of the: (a) Sample itself (b) Container holding the sample (c) Balance pan (d) Standard weight used for calibration
183. In size exclusion chromatography, the elution volume of a molecule is related to its ability to: (a) Bind to the stationary phase (b) Enter the pores of the stationary phase beads (c) Interact hydrophobically with the matrix (d) Carry an electrical charge
184. The isosbestic point in spectrophotometry is a wavelength at which: (a) The absorbance is zero (b) Two or more species have the same molar absorptivity (c) The transmittance is maximum (d) The detector sensitivity is highest
185. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used for: (a) Analyzing liquid samples directly (b) Elemental analysis of solid samples without prior dissolution (c) Identifying organic compounds in complex matrices (d) Measuring isotopic ratios in gases
186. A photoionization detector (PID) in gas chromatography is commonly used for detecting: (a) Non-polar hydrocarbons (b) Polar and aromatic compounds (c) Halogenated substances (d) Compounds containing sulfur and phosphorus
187. Chromatin immunoprecipitation (ChIP) is a technique used to investigate: (a) RNA-protein interactions (b) DNA-protein interactions in vivo (c) Protein-protein interactions in vitro (d) The methylation status of DNA
188. In normal-phase chromatography, more polar analytes tend to be retained: (a) Less strongly and elute earlier (b) More strongly and elute later (c) Independent of their polarity (d) Only if the mobile phase is nonpolar
189. The depth of field in microscopy refers to the: (a) Total magnification achievable (b) Thickness of the specimen that is simultaneously in focus (c) Distance between the objective lens and the specimen (d) Ability to distinguish between two closely spaced objects
190. Scanning electrochemical microscopy (SECM) is used to study: (a) The optical properties of surfaces (b) Electrochemical activity at interfaces with high spatial resolution (c) The magnetic properties of materials (d) The thermal conductivity of samples
191. To prepare a solution with a specific normality, you need to consider the: (a) Molecular weight of the solute (b) Equivalent weight of the solute (c) Molar mass of the solvent (d) Density of the solution
192. Membrane filtration is used for: (a) Sterilizing heat-stable powders (b) Removing microorganisms and particles from heat-sensitive liquids (c) Inactivating viruses in solutions (d) Drying laboratory glassware
193. When a fire alarm sounds in the laboratory, the first step should be to: (a) Try to extinguish the fire (b) Secure your experiment and then evacuate (c) Immediately evacuate the building (d) Call the fire department from your lab phone
194. The resolution of centrifugation depends on factors such as: (a) The material of the centrifuge tubes (b) The color of the sample (c) The viscosity of the medium and the time of centrifugation (d) The type of balance used to weigh the samples
195. In isoelectric focusing, proteins migrate through a pH gradient until they reach a pH equal to their: (a) Molecular weight (b) Isoelectric point (c) Charge at pH 7 (d) Hydrophobicity index
196. Auger electron spectroscopy (AES) analyzes the energy of electrons emitted due to: (a) Absorption of X-rays (b) Bombardment by ions (c) Relaxation of atoms after core-level ionization (d) Heating the sample in a vacuum
197. A thermal desorption system coupled to a gas chromatograph (TD-GC) is used for analyzing: (a) Non-volatile solids (b) Volatile and semi-volatile organic compounds trapped on an adsorbent (c) High molecular weight polymers (d) Inorganic gases
198. Fluorescence in situ hybridization (FISH) is a technique used to: (a) Detect specific protein sequences in cells (b) Visualize specific DNA or RNA sequences in cells or tissues (c) Measure the enzymatic activity within cells (d) Separate chromosomes based on size
199. Flow cytometry data is typically presented as: (a) A chromatogram with peaks corresponding to different analytes (b) A spectrum showing absorbance or emission versus wavelength (c) Histograms or dot plots showing the distribution of cell properties (d) An image of cells captured under a microscope
200. A refractometer is often used to determine the concentration of: (a) Proteins (b) Nucleic acids (c) Dissolved solids in a liquid (d) Gases

201. A serological pipette is typically used for: (a) Delivering a single, fixed volume of liquid with high accuracy (b) Transferring variable volumes of liquid, often with graduations to the tip (c) Measuring very small volumes in the microliter range (d) Mixing solutions by repeated aspiration and dispensing
202. When using a top-loading balance, the sample should be placed: (a) In the center of the pan (b) Towards the back of the pan (c) Towards the front of the pan (d) Anywhere on the pan as long as it doesn’t fall off
203. In gel permeation chromatography (GPC), which is a type of size exclusion chromatography, the stationary phase is typically composed of: (a) A charged matrix (b) A hydrophobic resin (c) Porous polymer beads (d) Ligand-bound particles
204. The sensitivity of a spectrophotometer refers to its ability to: (a) Measure the absorbance of highly concentrated solutions accurately (b) Detect small amounts of the analyte (c) Resolve closely spaced peaks in a spectrum (d) Operate over a wide range of wavelengths
205. Inductively coupled plasma (ICP) is a type of: (a) Detector used in mass spectrometry (b) Ionization source used in atomic emission and mass spectrometry (c) Stationary phase in chromatography (d) Light source in spectrophotometry
206. A micro-thermal conductivity detector ($\mu$TCD) in gas chromatography is characterized by its: (a) High sensitivity to hydrocarbons (b) Small size and low power consumption (c) Specificity to halogenated compounds (d) Ability to detect high molecular weight analytes
207. Yeast two-hybrid assay is a technique used to study: (a) DNA replication in yeast (b) Protein-protein interactions in yeast (c) Gene expression regulation in yeast (d) The mating process in yeast
208. In ion chromatography, separation is based on the: (a) Size of the ions (b) Charge and size of the ions interacting with a charged stationary phase (c) Hydrophobicity of the ions (d) Volatility of the ionic compounds
209. The condenser of a light microscope is used to: (a) Magnify the image (b) Focus light onto the specimen (c) Increase the resolution (d) Adjust the brightness of the field of view
210. Transmission electron microscopy (TEM) requires samples to be: (a) Coated with a heavy metal (b) Viewed in their native, hydrated state (c) Very thin to allow electrons to pass through (d) Stained with fluorescent dyes
211. When preparing a solution with a given normality, you need to know the number of: (a) Moles of solute (b) Gram equivalent weights of solute (c) Moles of solvent (d) Total ions in the solution
212. Filtration using a HEPA filter is primarily used to remove: (a) Viruses (b) Dissolved gases (c) Particulate matter, including bacteria and spores (d) Small molecules
213. In the event of an acid spill on your skin, the immediate action should be to: (a) Neutralize it with a base (b) Apply a burn ointment (c) Flush the affected area with large amounts of water (d) Cover it with a dry cloth
214. The k factor in centrifugation relates the sedimentation rate to: (a) The rotor speed only (b) The viscosity of the solution only (c) The rotor’s geometry and speed (d) The density of the particles
215. Capillary gel electrophoresis (CGE) is used for separating: (a) Proteins based on isoelectric point (b) Nucleic acids and proteins based on size and charge in a gel-filled capillary (c) Small molecules based on volatility (d) Lipids based on hydrophobicity
216. X-ray diffraction (XRD) is a technique used to determine the: (a) Elemental composition of a material (b) Crystal structure and lattice parameters of a solid (c) Surface morphology at the nanometer scale (d) Presence of specific functional groups in a molecule
217. A Faraday cup detector in mass spectrometry measures the: (a) Kinetic energy of the ions (b) Current produced by ions hitting a collector plate (c) Mass-to-charge ratio directly (d) Abundance of metastable ions
218. Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) is used for analyzing: (a) Thermally stable volatile compounds (b) Non-volatile solids and liquids by thermal decomposition followed by GC-MS analysis (c) Polar ionic compounds (d) Proteins and peptides
219. Biolayer interferometry (BLI) is a label-free technology used to study: (a) Nucleic acid hybridization (b) Protein folding (c) Biomolecular interactions in real-time (d) Cell migration
220. A particle size analyzer typically uses techniques such as: (a) Mass spectrometry (b) Dynamic light scattering or laser diffraction (c) Nuclear magnetic resonance (d) Atomic absorption spectroscopy
221. A Mohr pipette differs from a serological pipette in that a Mohr pipette: (a) Has graduations to the tip and is blown out (b) Does not have graduations to the tip and drains by gravity (c) Is used for more viscous liquids (d) Can measure smaller volumes more accurately
222. When using an analytical balance, it is important to: (a) Open all the doors to allow for air circulation (b) Ensure the balance is in a draft-free environment (c) Place the sample directly on the pan without a container (d) Calibrate it only once a year
223. In hydrophobic interaction chromatography, elution of bound proteins is typically achieved by: (a) Increasing the salt concentration (b) Decreasing the salt concentration (c) Changing the pH to the isoelectric point (d) Adding a denaturing agent
224. The limit of detection (LOD) of an analytical instrument is the: (a) Highest concentration that can be accurately measured (b) Lowest concentration that can be reliably distinguished from a blank (c) Range of concentrations over which the instrument response is linear (d) Precision of the instrument at high concentrations
225. Glow discharge mass spectrometry (GD-MS) is primarily used for the analysis of: (a) Organic compounds in solution (b) Solid materials, often for elemental composition (c) Gases and volatile liquids (d) Biomolecules such as proteins
226. A surface acoustic wave (SAW) sensor is a type of detector that responds to changes in: (a) Optical absorbance (b) Electrical conductivity (c) Mass loading on a piezoelectric crystal (d) Temperature
227. Reporter gene assays are used to study: (a) Protein folding pathways (b) Gene expression regulation (c) DNA replication fidelity (d) Enzyme kinetics
228. Field flow fractionation (FFF) separates particles based on their: (a) Charge in an electric field (b) Size and density in a flow stream under an external field (c) Binding affinity to a stationary phase (d) Volatility in a gas stream
229. A scanning laser confocal microscope uses a laser as the light source and a: (a) Wide-field detector (b) Point detector with a pinhole aperture (c) Transmission detector (d) Scanning electron detector
230. Ellipsometry is an optical technique used to measure the: (a) Refractive index of liquids (b) Thickness and optical properties of thin films (c) Surface roughness of materials (d) Fluorescence lifetime of molecules
231. A Kirkegaard & Perry Laboratories (KPL) substrate is often used in: (a) PCR (b) ELISA (c) Gel electrophoresis (d) Mass spectrometry
232. When using a microcentrifuge, it is important to: (a) Only centrifuge one tube at a time (b) Ensure the rotor is balanced by placing tubes with equal weights opposite each other (c) Fill the tubes completely to prevent collapse (d) Use the highest speed setting for all samples
233. Hydroxyapatite chromatography is used to separate proteins based on their: (a) Size (b) Charge and affinity for calcium phosphate (c) Hydrophobicity (d) Binding to specific ligands
234. The linearity of an analytical method refers to its ability to: (a) Provide results close to the true value (b) Give consistent results upon repeated measurements (c) Yield test results that are directly proportional to the concentration of the analyte (d) Detect very small amounts of the analyte
235. Secondary neutral mass spectrometry (SNMS) is similar to SIMS but uses: (a) Ions with higher kinetic energy (b) Neutral atoms for sputtering the surface (c) A magnetic sector mass analyzer (d) A time-of-flight mass analyzer
236. A surface plasmon resonance (SPR) sensor is used to study: (a) The magnetic properties of surfaces (b) Interactions between molecules in real-time by detecting changes in refractive index at a sensor surface (c) The topography of surfaces at the atomic level (d) The elemental composition of thin films
237. Luciferase assays are commonly used to study: (a) Protein degradation (b) Gene expression (c) Enzyme kinetics (d) Cell viability
238. Dielectrophoresis separates particles based on their: (a) Size in a flow field (b) Movement in a non-uniform electric field (c) Density in a centrifugal field (d) Charge in a uniform electric field
239. Two-photon excitation microscopy offers advantages over confocal microscopy, such as: (a) Higher spatial resolution (b) Reduced photobleaching and deeper penetration into tissues (c) Simpler optical setup (d) Lower cost
240. X-ray photoelectron spectroscopy (XPS) is a surface-sensitive technique that provides information about: (a) The bulk elemental composition (b) The oxidation states and elemental composition of the surface (c) The crystal structure (d) The magnetic properties
241. A Kjeldahl flask is specifically used for: (a) Titrations involving iodine (b) Digesting samples with strong acids at high temperatures, often for nitrogen determination (c) Storing light-sensitive chemicals (d) Collecting gases evolved from a reaction
242. When using a safety shower in the lab, you should: (a) Use it briefly to rinse off any visible contamination (b) Remove contaminated clothing while under the shower and continue for at least 15 minutes (c) Use cold water to minimize skin irritation (d) Only use it if someone else is present to assist you
243. Immunoaffinity chromatography uses an antibody specific to the target molecule that is: (a) Mixed with the sample in solution (b) Covalently bound to the stationary phase (c) Added to the mobile phase (d) Used to elute the bound molecules
244. The working range of an analytical instrument is the: (a) Set of conditions (e.g., temperature, pressure) under which the instrument can operate (b) Concentration range over which the instrument provides reliable quantitative results (c) Time period for which the instrument can be used continuously (d) Smallest and largest values that the instrument can measure
245. Accelerator mass spectrometry (AMS) is particularly useful for measuring: (a) Stable isotopes with high precision (b) Long-lived radionuclides at very low concentrations (c) The mass of large biomolecules (d) The isotopic abundance of light elements
246. A quartz crystal microbalance (QCM) is a highly sensitive technique for measuring: (a) Changes in temperature (b) Changes in mass on the surface of the crystal (c) Changes in refractive index (d) Changes in electrical conductivity
247. Flow injection analysis (FIA) is an automated technique for: (a) Separating complex mixtures (b) Performing rapid chemical analyses of solutions (c) Imaging microscopic samples (d) Determining the structure of molecules
248. Isotachophoresis separates ions based on their: (a) Size and shape (b) Electrophoretic mobility in a discontinuous buffer system (c) Affinity for a stationary phase (d) Density
249. Stimulated emission depletion (STED) microscopy achieves super-resolution by: (a) Illuminating the sample with structured light (b) Using two photons for excitation (c) Depleting the fluorescence at the periphery of the excitation spot (d) Analyzing the temporal fluctuations of fluorescence
250. Grazing-incidence small-angle X-ray scattering (GISAXS) is used to study: (a) The bulk structure of crystalline materials (b) Nanoscale structures at surfaces and interfaces (c) The elemental composition of thin films (d) The vibrational modes of molecules

251. A Soxhlet extractor is used for: (a) Rapid heating of solvents (b) Continuous extraction of a compound from a solid material using a solvent (c) Precise distillation of liquids (d) Filtering large volumes of solutions
252. When disposing of chemical waste, it is crucial to: (a) Pour everything down the drain with plenty of water (b) Mix all waste together to save space (c) Follow the specific disposal guidelines for each type of chemical (d) Leave it for the next person to handle
253. A desalting column, often using gel filtration media, is used to remove: (a) Proteins (b) Nucleic acids (c) Small molecules like salts from larger molecules (d) Lipids
254. The signal-to-noise ratio (S/N) is a measure of: (a) The accuracy of an instrument (b) The precision of a measurement (c) The quality of the analytical signal compared to background noise (d) The sensitivity of the detector
255. Laser-induced breakdown spectroscopy (LIBS) is an atomic emission technique that analyzes the elemental composition of a sample by: (a) Heating it in a furnace (b) Bombarding it with electrons (c) Focusing a pulsed laser beam onto it to create a plasma (d) Passing X-rays through it
256. An olfactometry port connected to a gas chromatograph (GC-O) allows for: (a) Simultaneous mass spectrometry and flame ionization detection (b) The sniffing of the GC effluent to detect odor-active compounds (c) Automated injection of multiple samples (d) Precise control of the column temperature program
257. Phage display is a technique used to study: (a) Bacterial growth kinetics (b) Protein-protein, protein-peptide, and other molecular interactions (c) Viral replication mechanisms (d) DNA sequencing
258. Capillary isoelectric focusing (cIEF) is a high-resolution technique for separating proteins based on their: (a) Size (b) Isoelectric point (c) Hydrophobicity (d) Binding affinity
259. Structured illumination microscopy (SIM) achieves super-resolution by: (a) Using a doughnut-shaped laser beam to deplete fluorescence (b) Illuminating the sample with patterned light and computationally reconstructing the image (c) Exciting fluorophores with two photons simultaneously (d) Analyzing the blinking of individual fluorophores
260. Total internal reflection fluorescence microscopy (TIRFM) selectively illuminates: (a) The entire volume of the cell (b) A thin region close to the coverslip surface (c) Only the nucleus of the cell (d) Extracellular matrix components
261. A separatory funnel is used for: (a) Heating liquids uniformly (b) Separating immiscible liquids (c) Filtering precipitates (d) Storing volatile chemicals
262. When using a Bunsen burner, the hottest part of the flame is usually the: (a) Tip of the inner blue cone (b) Outer yellow region (c) Base of the flame (d) Entire flame is uniformly hot
263. A dialysis membrane is used to separate molecules based on their: (a) Charge (b) Size (c) Hydrophobicity (d) Binding affinity
264. The dynamic range of an analytical instrument refers to the: (a) Smallest and largest values it can measure (b) Range of analyte concentrations over which the instrument response is useful (c) Speed at which it can take measurements (d) Stability of the instrument over time
265. Secondary electron microscopy (SEM) primarily provides information about the: (a) Internal structure of a sample (b) Surface topography of a sample (c) Elemental composition of a sample (d) Crystal structure of a sample
266. A purge and trap system coupled to a gas chromatograph (P&T-GC) is used for concentrating: (a) High boiling point compounds from a liquid matrix (b) Volatile organic compounds from liquid or solid samples (c) Polar ionic species (d) Large biomolecules
267. Surface plasmon resonance imaging (SPRi) allows for the simultaneous study of: (a) Multiple molecular interactions on a sensor chip (b) The three-dimensional structure of a single molecule (c) The elemental composition across a surface (d) The magnetic domains of a material
268. Microarray technology is used for: (a) Sequencing a single gene rapidly (b) Simultaneously analyzing the expression of thousands of genes (c) Separating proteins based on size (d) Amplifying specific DNA sequences
269. Single-molecule localization microscopy (SMLM) achieves super-resolution by: (a) Using structured illumination patterns (b) Exciting fluorophores with two photons (c) Precisely determining the positions of individual, sparsely activated fluorophores over time (d) Depleting fluorescence with a STED beam
270. Atomic emission spectroscopy (AES) relies on measuring the light emitted by atoms that have been: (a) Absorbed by the sample (b) Scattered by the sample (c) Excited to a higher energy level (d) Passed through a magnetic field
271. A mortar and pestle is used for: (a) Heating solids to high temperatures (b) Grinding and mixing solid substances (c) Precisely measuring volumes of powders (d) Filtering viscous liquids
272. When smelling a chemical in the lab, you should: (a) Take a deep breath directly over the container (b) Gently waft the vapors towards your nose with your hand (c) Smell it only if it is known to be safe (d) Avoid smelling any lab chemicals
273. Lyophilization (freeze-drying) is a method used for: (a) Rapidly freezing samples for cryo-EM (b) Removing water from a sample to preserve it (c) Sterilizing heat-sensitive biological materials (d) Lysing cells to extract DNA or RNA
274. The robustness of an analytical method refers to its ability to: (a) Be unaffected by small, deliberate variations in method parameters (b) Provide accurate results for a wide range of sample matrices (c) Detect very low concentrations of the analyte (d) Be easily implemented in different laboratories
275. Electron microprobe analysis (EMPA) is used to: (a) Image surfaces at high resolution (b) Determine the elemental composition of microscopic volumes of a solid sample (c) Analyze the crystal structure of materials (d) Measure the magnetic properties of thin films
276. Headspace gas chromatography (HS-GC) is used for analyzing: (a) Non-volatile compounds in a liquid matrix (b) Volatile compounds that partition into the gas phase above a sample (c) Polar ionic compounds (d) High molecular weight polymers
277. Impedance spectroscopy measures the electrical impedance of a system as a function of: (a) Applied voltage (b) Frequency of the applied AC signal (c) Current flow (d) Temperature
278. RNA sequencing (RNA-Seq) is used to: (a) Determine the sequence of a specific RNA molecule (b) Analyze the transcriptome, the set of all RNA molecules in a cell or population of cells (c) Detect specific RNA sequences in situ (d) Measure the stability of RNA molecules
279. Förster resonance energy transfer (FRET) is a technique used to study: (a) The movement of single molecules (b) Interactions and distances between fluorescently labeled molecules (c) The binding of ligands to receptors (d) Changes in membrane potential
280. Secondary ion mass spectrometry (SIMS) is particularly useful for: (a) Analyzing volatile organic compounds (b) Surface analysis and elemental or isotopic mapping (c) Determining the molecular weight of polymers (d) Analyzing gases
281. A Buchner funnel is used for: (a) Heating liquids in a controlled manner (b) Filtering larger quantities of solid-liquid mixtures under vacuum (c) Precise addition of liquids dropwise (d) Measuring the density of powders
282. When working with glassware under vacuum, it is important to: (a) Heat it gently to remove any moisture (b) Ensure it is free of cracks or chips (c) Wrap it in a protective layer (d) Use thick-walled glassware specifically designed for vacuum
283. Solid phase extraction (SPE) is a sample preparation technique used to: (a) Increase the solubility of a sample (b) Separate analytes of interest from a complex matrix based on their physical and chemical properties (c) Homogenize solid samples (d) Concentrate volatile compounds
284. The selectivity of an analytical method refers to its ability to: (a) Detect small changes in the concentration of an analyte (b) Measure the analyte of interest without interference from other components in the sample (c) Provide consistent results over time (d) Be applicable to a wide range of sample types
285. Transmission electron microscopy (TEM) uses a beam of: (a) Light (b) Electrons (c) X-rays (d) Ions
286. Thermal gravimetric analysis (TGA) measures the: (a) Heat flow into or out of a sample as a function of temperature or time (b) Change in mass of a sample as a function of temperature or time (c) Mechanical properties of a sample as a function of temperature (d) Optical properties of a sample as a function of temperature
287. A flame atomic absorption spectrometer (FAAS) typically uses a flame to: (a) Excite the atoms so they emit light (b) Ionize the atoms for mass analysis (c) Atomize the sample (d) Detect the light absorbed by the atoms
288. DNA footprinting is a technique used to identify: (a) The sequence of a DNA molecule (b) The binding site of a protein on a DNA molecule (c) The methylation status of DNA (d) DNA-RNA hybrids
289. Patch-clamp technique is used to study: (a) The movement of organelles within a cell (b) The electrical properties of cell membranes and single ion channels (c) The synthesis of proteins in real-time (d) The diffusion of molecules across a membrane
290. Atomic force microscopy (AFM) can be used to study: (a) Only conductive surfaces (b) Both conductive and non-conductive surfaces at high resolution (c) The elemental composition of surfaces (d) The chemical bonds within a molecule
291. A Kjeldahl digestion converts nitrogen in a sample into: (a) Nitrate ions (b) Nitrite ions (c) Ammonium ions (d) Nitrogen gas
292. When diluting a concentrated base, you should always add: (a) Water to the base quickly (b) Base to water slowly and with stirring (c) The base and water simultaneously (d) Water to the base slowly
293. Gas chromatography-infrared spectroscopy (GC-IR) combines the separation power of GC with the structural information from IR to identify: (a) Elements (b) Isotopes (c) Compounds (d) Molecular weight
294. The accuracy of an analytical method is often expressed in terms of: (a) Standard deviation (b) Relative standard deviation (c) Percent recovery (d) Limit of detection
295. Scanning tunneling microscopy (STM) relies on the principle of: (a) Electron diffraction (b) Quantum tunneling (c) Fluorescence emission (d) Atomic absorption
296. Differential scanning calorimetry (DSC) measures the: (a) Temperature at which a phase transition occurs (b) Rate of change of temperature of a sample (c) Difference in heat flow between a sample and a reference as a function of temperature (d) Change in mass of a sample during heating
297. A hydride generation system is used in atomic absorption spectroscopy to analyze elements such as: (a) Sodium and potassium (b) Calcium and magnesium (c) Arsenic and selenium (d) Iron and copper
298. Enzyme-linked immunospot (ELISpot) primarily detects: (a) Intracellular proteins (b) Secreted molecules from individual cells (c) Cell surface antigens (d) Nucleic acid sequences
299. Live cell imaging often utilizes techniques such as: (a) Electron microscopy (b) Fluorescence microscopy with time-lapse capabilities (c) Atomic force microscopy in contact mode (d) X-ray crystallography
300. A Langmuir-Blodgett trough is used for: (a) Growing single crystals (b) Preparing ordered monolayers of molecules (c) Separating lipids by electrophoresis (d) Measuring surface tension of liquids

301. A Soxhlet apparatus is typically used for the extraction of: (a) Volatile liquids (b) Non-volatile solids (c) Gases dissolved in liquids (d) Heat-sensitive compounds
302. In case of a minor cut in the lab, the first step should be to: (a) Apply antiseptic cream immediately (b) Inform the lab instructor (c) Wash the wound with soap and water (d) Cover it tightly with a bandage
303. Ion-pairing chromatography is a type of HPLC used to separate: (a) Large polymers (b) Charged analytes (c) Hydrophobic molecules (d) Volatile compounds
304. The limit of quantification (LOQ) of an analytical method is the: (a) Lowest concentration that can be detected (b) Lowest concentration that can be measured with acceptable accuracy and precision (c) Highest concentration that can be measured accurately (d) Range over which the method is linear
305. Reflection electron microscopy (REM) is used to study the: (a) Internal structure of thin samples (b) Surface of bulk samples (c) Elemental composition (d) Crystal lattice
306. Thermomechanical analysis (TMA) measures the: (a) Electrical properties of a material as a function of temperature (b) Dimensional changes of a material as a function of temperature (c) Optical properties of a material as a function of temperature (d) Mass changes of a material as a function of temperature
307. Inductively coupled plasma optical emission spectrometry (ICP-OES) measures the: (a) Absorption of light by atoms in a plasma (b) Emission of light by excited atoms in a plasma (c) Mass-to-charge ratio of ions from a plasma (d) Scattering of light by particles in a plasma
308. DNAse footprinting is used to identify: (a) DNA methylation sites (b) DNA-protein binding sites (c) RNA-DNA hybrids (d) Supercoiled DNA regions
309. Electrophysiology techniques, such as patch-clamping, are crucial for studying: (a) Protein folding (b) Cellular electrical activity (c) DNA replication (d) Metabolic pathways
310. Near-field scanning optical microscopy (NSOM) can achieve resolution beyond the diffraction limit by: (a) Using electron beams instead of light (b) Illuminating the sample through a sub-wavelength aperture (c) Detecting fluorescence from the entire sample (d) Using confocal optics
311. A desiccator is used to: (a) Heat samples to high temperatures in a dry environment (b) Maintain a low-humidity environment for moisture-sensitive materials (c) Filter air to remove particulate matter (d) Stir solutions at a controlled rate
312. When using a centrifuge, proper balancing is essential to prevent: (a) Sample contamination (b) Damage to the centrifuge and uneven sedimentation (c) Temperature fluctuations within the rotor (d) Electrical hazards
313. Chiral chromatography is used to separate enantiomers based on their differential interaction with a: (a) Polar stationary phase (b) Nonpolar mobile phase (c) Chiral stationary phase (d) Size exclusion matrix
314. The ruggedness of an analytical method assesses its: (a) Sensitivity to small changes in method parameters (b) Accuracy under ideal conditions (c) Precision by different analysts in different labs (d) Linearity over a wide concentration range
315. Auger electron spectroscopy (AES) is sensitive to: (a) Bulk elemental composition (b) Surface elemental composition (c) Crystal structure (d) Magnetic properties
316. Dynamic mechanical analysis (DMA) measures the: (a) Thermal transitions of a material (b) Mechanical properties of a material under oscillatory load as a function of temperature or frequency (c) Electrical conductivity as a function of temperature (d) Optical absorbance as a function of wavelength
317. A Zeeman correction is used in atomic absorption spectroscopy to correct for: (a) Spectral interferences (b) Non-atomic absorption (c) Chemical interferences (d) Ionization interferences
318. RNA interference (RNAi) is a biological process used to: (a) Amplify specific RNA sequences (b) Silence gene expression by degrading specific mRNA molecules (c) Introduce mutations into RNA (d) Label RNA molecules with fluorescent tags
319. Calcium imaging often uses fluorescent dyes that change their emission properties upon binding to calcium ions, allowing for the visualization of: (a) Protein localization (b) Intracellular calcium dynamics (c) Membrane potential changes (d) DNA replication sites
320. A Brewster angle microscope is used to image: (a) Atomic lattices of crystals (b) Monolayers at the air-liquid interface (c) Sub-cellular organelles with high resolution (d) Magnetic domains on surfaces
321. A separatory funnel should be vented periodically when used for extraction with volatile solvents to prevent: (a) Oxidation of the solvent (b) Pressure buildup (c) Formation of emulsions (d) Loss of analyte
322. When heating a test tube containing a liquid over a Bunsen burner, you should: (a) Point the open end towards yourself (b) Hold it stationary in the hottest part of the flame (c) Gently heat the sides and move the tube to distribute the heat (d) Stopper the tube to prevent evaporation
323. High-performance ion exchange chromatography (HPIEC) is used for the separation of: (a) Lipids (b) Proteins and nucleic acids based on charge (c) Small neutral molecules (d) Volatile organic compounds
324. Method validation in analytical chemistry is the process of: (a) Developing a new analytical method (b) Determining the performance characteristics of a method to ensure its reliability for its intended purpose (c) Using a method for routine sample analysis (d) Comparing different analytical methods
325. Scanning Auger microscopy (SAM) combines Auger electron spectroscopy with scanning electron microscopy to provide: (a) High-resolution images of surface topography (b) Spatially resolved elemental analysis of surfaces (c) Information about the bulk composition (d) Crystal structure determination
326. Modulated differential scanning calorimetry (MDSC) allows for the separation of the heat flow into: (a) Endothermic and exothermic components (b) Reversing and non-reversing components (c) High and low temperature components (d) Sample and reference components
327. Electrothermal atomic absorption spectroscopy (ETAAS) uses a: (a) Flame to atomize the sample (b) Graphite furnace to atomize the sample (c) Plasma to excite the atoms (d) Laser to ablate the sample
328. RNA sequencing by in situ hybridization (RNA-Seq ISH) allows for: (a) High-throughput sequencing of purified RNA (b) Visualization and quantification of RNA transcripts within their cellular context (c) Amplification of RNA from single cells (d) Analysis of RNA secondary structure
329. Total internal reflection microscopy (TIRM) is used to study: (a) The bulk properties of materials (b) Interactions at surfaces, such as cell adhesion (c) The internal structure of organelles (d) The flow of fluids in microchannels
330. A surface force apparatus (SFA) is used to directly measure: (a) The topography of surfaces at atomic resolution (b) Forces between surfaces at the nanometer scale (c) The chemical composition of surfaces (d) The optical properties of thin films
331. A rotary evaporator is used to: (a) Mix solutions at high speeds (b) Remove solvents from solutions under reduced pressure (c) Dry solid samples in a vacuum oven (d) Separate immiscible liquids
332. When working with electrical equipment in the lab, it is important to: (a) Use extension cords whenever necessary (b) Ensure your hands are dry (c) Overload circuits if needed (d) Ignore frayed or damaged cords if the equipment is working
333. Hydrophilic interaction chromatography (HILIC) is a variant of normal-phase liquid chromatography particularly useful for separating: (a) Nonpolar compounds (b) Hydrophilic compounds (c) Large biomolecules (d) Volatile analytes
334. Quality control (QC) in an analytical lab involves: (a) Developing new analytical methods (b) Implementing procedures to ensure the reliability of test results (c) Publishing research findings (d) Ordering laboratory supplies
335. Ion microscopy uses: (a) Light to image the sample (b) Ions to sputter and analyze the sample surface (c) Electrons that have passed through the sample (d) X-rays to create an image
336. Photoacoustic spectroscopy measures: (a) The light absorbed by a sample directly (b) The sound waves generated by a sample upon absorption of modulated light (c) The fluorescence emitted by a sample (d) The scattering of light by a sample
337. A cold vapor atomic absorption spectroscopy (CVAAS) technique is specifically used for the analysis of: (a) Lead (b) Mercury (c) Cadmium (d) Chromium
338. Yeast three-hybrid system is used to study: (a) Protein folding (b) RNA-protein interactions (c) DNA-protein interactions (d) Protein-protein interactions
339. Atomic layer deposition (ALD) is a technique for: (a) Etching materials at the nanoscale (b) Growing thin films with atomic-level precision (c) Analyzing the elemental composition of surfaces (d) Imaging surfaces with high resolution
340. Brillouin microscopy is used to measure the: (a) Chemical composition of a sample at high resolution (b) Mechanical properties (e.g., elasticity) of materials and biological samples by analyzing scattered light (c) Electrical conductivity of microscopic structures (d) Magnetic domains within a material
341. A Soxhlet extraction is typically a (an): (a) Very rapid extraction method (b) Semi-automated continuous extraction method (c) Manual single-step extraction (d) Method for extracting volatile compounds only
342. If you get a chemical in your eye, the first thing to do is: (a) Try to neutralize it with another chemical (b) Rub your eye gently (c) Flush your eye immediately with plenty of water for at least 15 minutes (d) Seek help from a colleague
343. Supercritical fluid chromatography (SFC) combines aspects of: (a) Gas and liquid chromatography (b) Thin layer and column chromatography (c) Ion exchange and size exclusion chromatography (d) Normal and reversed-phase chromatography
344. A control chart in quality control is used to: (a) Calibrate analytical instruments (b) Monitor the stability and performance of an analytical process over time (c) Train new laboratory personnel (d) Record the results of each analysis
345. Helium ion microscopy (HIM) uses a focused beam of helium ions to: (a) Transmit through thin samples (b) Image the surface of samples with high resolution and surface sensitivity (c) Determine the elemental composition (d) Analyze the crystal structure
346. Electron energy loss spectroscopy (EELS) is often used in conjunction with TEM to: (a) Enhance image contrast (b) Obtain information about the elemental composition and electronic structure of a sample (c) Increase the magnification (d) Reduce sample charging
347. A inductively coupled plasma mass spectrometer (ICP-MS) uses an ICP to: (a) Separate ions based on their mass-to-charge ratio (b) Ionize atoms of the sample for mass analysis (c) Excite atoms to emit light (d) Atomize the sample for absorption measurements
348. Chromosome conformation capture (3C) and related techniques are used to study: (a) DNA methylation patterns across the genome (b) The three-dimensional organization of the genome (c) RNA-DNA interactions (d) The sequence of repetitive DNA elements
349. Optical coherence tomography (OCT) is an imaging technique used to obtain: (a) High-resolution images of the surface of opaque materials (b) Cross-sectional images of biological tissues with micrometer-scale resolution (c) Real-time images of molecular interactions (d) Three-dimensional reconstructions from electron microscopy
350. A Langmuir isotherm describes the: (a) Rate of a chemical reaction at a surface (b) Adsorption of a gas onto a solid surface forming a monolayer (c) Emission of electrons from a heated surface (d) Diffraction of X-rays by a crystal lattice

351. A Dean-Stark apparatus is used for: (a) Rapid stirring of magnetic solutions (b) Removing water or other immiscible liquids from a reaction mixture by azeotropic distillation (c) Precise temperature control of a reaction (d) Filtering air-sensitive compounds
352. When a strong base is spilled on the bench, it should be neutralized with: (a) Water (b) A strong acid (c) A weak acid like acetic acid or citric acid (d) A strong oxidizing agent
353. Size exclusion chromatography is also known as: (a) Ion exchange chromatography (b) Affinity chromatography (c) Gel permeation or gel filtration chromatography (d) Partition chromatography
354. The accuracy of an analytical result can be assessed by: (a) Performing replicate measurements (b) Calculating the standard deviation (c) Analyzing a standard reference material (d) Determining the limit of detection
355. Low-energy electron diffraction (LEED) is a surface-sensitive technique used to determine the: (a) Elemental composition of the surface (b) Arrangement of atoms on the surface of a single crystal (c) Electronic band structure of the material (d) Magnetic order at the surface
356. Thermogravimetric analysis coupled with mass spectrometry (TGA-MS) allows for the simultaneous measurement of: (a) Mass change and heat flow (b) Mass change and the identification of evolved gases (c) Heat flow and evolved gases (d) Dimensional changes and mass change
357. A hollow cathode lamp is a light source used in: (a) UV-Vis spectrophotometry (b) Atomic absorption spectroscopy (c) Fluorescence spectroscopy (d) Raman spectroscopy
358. Yeast one-hybrid system is used to study: (a) Protein-protein interactions (b) DNA-protein interactions (c) RNA-protein interactions (d) Protein localization
359. Multiphoton microscopy, compared to confocal microscopy, typically offers: (a) Higher spatial resolution (b) Greater penetration depth in scattering tissues (c) Simpler instrumentation (d) Reduced photobleaching in the illuminated plane
360. Scanning near-field acoustic microscopy (SNAM) is used to image: (a) The optical properties of surfaces at nanoscale (b) Subsurface structures and mechanical properties by detecting acoustic waves (c) The magnetic domains of materials (d) The thermal conductivity of samples
361. A Schlenk line is used in the laboratory for working with: (a) Radioactive materials (b) Air-sensitive compounds (c) High-pressure reactions (d) Cryogenic liquids
362. When using a magnetic stirrer, the speed of stirring is controlled by: (a) The size of the stir bar (b) The viscosity of the solution (c) Adjusting the current to the motor (d) The temperature of the solution
363. Thin layer chromatography (TLC) separates compounds based on their differential migration on a stationary phase due to differences in: (a) Molecular weight (b) Polarity and solubility in the mobile phase (c) Electrical charge (d) Volatility
364. The precision of an analytical result is often expressed as: (a) Percent recovery (b) Standard error of the mean (c) Relative standard deviation (d) Accuracy
365. Ion scattering spectroscopy (ISS) is a surface analysis technique that involves bombarding the surface with ions and analyzing the: (a) Emitted secondary electrons (b) Scattered primary ions (c) Emitted photons (d) Transmitted ions
366. Evolved gas analysis (EGA) coupled with mass spectrometry involves: (a) Measuring the mass of a sample as a function of temperature (b) Heating a sample and analyzing the composition of the gases released (c) Separating gases by chromatography before mass analysis (d) Ionizing the sample directly in a mass spectrometer
367. A deuterium lamp is a common light source in: (a) Flame photometry (b) Atomic emission spectroscopy (c) UV spectrophotometry (d) Infrared spectroscopy
368. Reporter assays typically involve measuring the activity of an enzyme whose gene is linked to a promoter of interest, examples include: (a) Western blot and ELISA (b) Luciferase and β-galactosidase assays (c) PCR and RT-PCR (d) Flow cytometry and microscopy
369. Light sheet microscopy (also known as SPIM) reduces photobleaching by: (a) Using very short excitation wavelengths (b) Illuminating only a thin plane of the sample perpendicular to the detection axis (c) Detecting fluorescence from the entire sample simultaneously (d) Using very low intensity light sources
370. Scanning thermal microscopy (SThM) is used to map the: (a) Chemical composition of a surface (b) Temperature and thermal conductivity of a surface at high spatial resolution (c) Electrical potential across a surface (d) Magnetic field above a surface
371. A Schlenk flask with a side arm is used for: (a) High-pressure reactions (b) Performing reactions under an inert atmosphere (c) Rapid cooling of reactions (d) Filtration of air-sensitive materials
372. The speed of a microcentrifuge is typically expressed in: (a) Revolutions per minute (RPM) or relative centrifugal force (RCF) (b) Meters per second (m/s) (c) Gravitational force (g) only (d) Hertz (Hz)
373. Paper chromatography separates compounds based on: (a) Molecular weight (b) Partitioning between a stationary liquid phase (water bound to the paper) and a mobile liquid phase (c) Electrical charge (d) Adsorption to the paper fibers
374. The robustness of an analytical method is evaluated by: (a) Comparing results with a reference method (b) Assessing the method’s capacity to remain unaffected by small but deliberate variations in method parameters (c) Determining the lowest amount of analyte that can be detected (d) Measuring the reproducibility of the results
375. Rutherford backscattering spectrometry (RBS) is used to determine the: (a) Surface morphology (b) Elemental composition and depth profiling of materials (c) Crystal structure (d) Electronic band structure
376. Pyrolysis-gas chromatography (Py-GC) is used for analyzing: (a) Volatile organic compounds (b) Non-volatile materials by thermally decomposing them into smaller volatile fragments for GC analysis (c) Polar ionic compounds (d) Gases
377. A tungsten lamp is a common light source in the: (a) UV region of spectrophotometry (b) Visible and near-infrared regions of spectrophotometry (c) Atomic absorption spectroscopy (d) Fluorescence microscopy
378. Split-luciferase complementation assay is used to study: (a) Protein degradation pathways (b) Protein-protein interactions by reconstituting a functional luciferase enzyme (c) Gene silencing mechanisms (d) DNA repair processes
379. Light field microscopy (also known as plenoptic microscopy) allows for: (a) Imaging beyond the diffraction limit (b) Capturing both spatial and angular information of light, enabling post-acquisition refocusing (c) High-speed imaging of single molecules (d) Deep penetration imaging of tissues
380. Scanning capacitance microscopy (SCM) is used to image: (a) The magnetic properties of surfaces (b) Variations in electrical capacitance at a surface, often related to dopant concentration in semiconductors (c) The topography of surfaces with atomic resolution (d) The thermal conductivity of materials
381. A round-bottom flask is often used for: (a) Precise volumetric measurements (b) Reactions that require heating or stirring (c) Storing corrosive chemicals (d) Filtering large volumes
382. The relative centrifugal force (RCF) is calculated using the formula: (a) RCF=ω2r (where ω is angular velocity, r is radius) (b) RCF=mrω2 (where m is mass) (c) RCF=ωr (d) RCF=rω2​
383. Two-dimensional gel electrophoresis typically involves separation by isoelectric focusing in the first dimension and SDS-PAGE in the second, separating proteins based on: (a) Size in both dimensions (b) Charge in both dimensions (c) Isoelectric point and then size (d) Hydrophobicity and then size
384. The intermediate check standard in quality control is used to: (a) Calibrate the instrument at the beginning of each run (b) Assess the precision of the method (c) Evaluate the accuracy of the method at a concentration within the calibration range (d) Determine the limit of detection
385. X-ray absorption spectroscopy (XAS) is used to determine the: (a) Crystal structure of a material (b) Electronic and local atomic structure around a specific element in a sample (c) Surface morphology at the nanoscale (d) Elemental composition of the bulk
386. Programmed temperature gas chromatography (PTGC) involves: (a) Injecting the sample at a high temperature (b) Varying the column temperature over time to improve separation (c) Using a temperature-controlled detector (d) Maintaining a constant carrier gas flow rate by adjusting temperature
387. A photomultiplier tube (PMT) is a very sensitive detector of light, often used in: (a) Atomic absorption spectroscopy (b) Fluorescence spectroscopy and scintillation counting (c) Infrared spectroscopy (d) Nuclear magnetic resonance spectroscopy
388. Bimolecular fluorescence complementation (BiFC) assay is used to visualize: (a) RNA-RNA interactions (b) Protein-DNA interactions (c) Protein-protein interactions by reconstituting a fluorescent protein (d) The localization of a single protein
389. Optical tweezers use a highly focused laser beam to: (a) Ablate microscopic samples (b) Trap and manipulate microscopic objects such as atoms and cells (c) Illuminate samples for super-resolution microscopy (d) Measure the refractive index of small particles
390. Scanning ion conductance microscopy (SICM) is used to image the topography of: (a) Conductive surfaces (b) Non-conductive surfaces in liquid environments by measuring ion current flow through a nanopipette (c) Magnetic materials (d) Samples under high vacuum
391. A Florence flask is typically used for: (a) Precise titrations (b) Uniform heating of liquids (c) Storing standard solutions (d) Filtration under vacuum
392. The g-force in centrifugation refers to: (a) The mass of the rotor (b) The gravitational force exerted on the sample (c) The ratio of the centrifugal acceleration to the standard acceleration due to gravity (d) The speed of rotation in RPM
393. Capillary zone electrophoresis (CZE) separates ions based on their: (a) Size (b) Charge-to-size ratio in a free solution within a capillary (c) Hydrophobicity (d) Binding affinity
394. A system suitability test is performed to: (a) Calibrate the analytical instrument (b) Ensure the analytical system is performing adequately at the time of analysis (c) Validate a new analytical method (d) Train new laboratory personnel
395. Extended X-ray absorption fine structure (EXAFS) provides information about: (a) The long-range order in crystalline materials (b) The local atomic environment around a selected absorber atom (c) The elemental composition of the surface (d) The electronic band structure
396. Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is used to determine the: (a) Concentration of compounds separated by GC (b) Isotopic composition of carbon (and other elements) in separated compounds (c) Molecular weight of GC eluents (d) Presence of specific functional groups
397. A charge-coupled device (CCD) detector is commonly used in spectroscopy and microscopy because of its: (a) High sensitivity and ability to detect a wide range of wavelengths simultaneously (b) Low cost and simplicity of operation (c) Ability to measure very high light intensities (d) Specificity to certain types of radiation
398. Split-GFP complementation assay is used to study: (a) RNA localization (b) DNA replication dynamics (c) Protein-protein interactions by reconstituting a functional green fluorescent protein (d) Membrane fluidity
399. Optical coherence microscopy (OCM) is a technique that combines optical coherence tomography with microscopy to provide: (a) High-resolution surface images (b) Cross-sectional images with cellular-level resolution (c) Three-dimensional reconstructions from electron microscopy data (d) Real-time tracking of single molecules
400. Kelvin probe force microscopy (KPFM) is used to measure the: (a) Magnetic force gradient above a surface (b) Surface potential or work function of a material with high spatial resolution (c) Friction forces at the nanoscale (d) Topography of surfaces in liquid environments

401. A Kjeldahl flask is specifically designed for: (a) Vacuum filtration (b) Strong acid digestion at high temperatures (c) Gentle heating of volatile liquids (d) Precise volumetric measurements
402. When working with potentially explosive chemicals, it is crucial to: (a) Store them in a fume hood (b) Handle them gently and avoid shock or friction (c) Heat them in a closed container (d) Mix them with inert materials for disposal
403. Micellar electrokinetic chromatography (MEKC) is a variant of capillary electrophoresis that allows for the separation of: (a) Only charged molecules (b) Both charged and neutral molecules based on their partitioning into micelles (c) Large biomolecules like proteins (d) Small volatile compounds
404. The method detection limit (MDL) is the: (a) Lowest concentration that can be routinely quantified (b) Minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero (c) Concentration at which the signal-to-noise ratio is 3:1 (d) Highest concentration that can be accurately measured
405. Transmission X-ray microscopy (TXM) is used to image samples by: (a) Scanning a focused X-ray beam and detecting emitted electrons (b) Measuring the absorption of X-rays passing through the sample (c) Detecting the diffraction pattern of X-rays scattered by the sample (d) Analyzing the fluorescence emitted upon X-ray excitation
406. Selected ion monitoring (SIM) in mass spectrometry enhances sensitivity by: (a) Scanning the entire mass range rapidly (b) Focusing on a few specific mass-to-charge ratios of interest (c) Using a more powerful ionization source (d) Increasing the resolution of the mass analyzer
407. A scintillation counter is used to detect and measure: (a) UV or visible light emitted by a sample (b) Radioactive decay by measuring the light produced when radiation interacts with a scintillator (c) Infrared radiation from a heated sample (d) The absorbance of a solution at different wavelengths
408. Förster resonance energy transfer (FRET) microscopy can be used to determine: (a) The concentration of a specific molecule (b) The distance between two fluorescently labeled molecules (c) The velocity of molecules within a cell (d) Changes in pH within organelles
409. Atomic beam epitaxy (ABE) is a technique used for: (a) Analyzing the surface composition of materials (b) Growing thin films with high purity and control at the atomic level (c) Etching surfaces with high precision (d) Measuring the electronic properties of interfaces
410. Scanning microwave microscopy (SMM) is used to image: (a) The optical properties of materials at microwave frequencies (b) The electrical properties (e.g., capacitance, conductance) of surfaces with high spatial resolution (c) The magnetic domains within a sample (d) The thermal conductivity at the nanoscale
411. A Soxhlet extraction is often used for determining the: (a) Water content of a sample (b) Fat content of a solid food sample (c) Ash content of a material (d) Molecular weight of a polymer
412. Safety glasses should be worn in the lab: (a) Only when handling hazardous chemicals (b) Only when using heating devices (c) At all times (d) Only when explicitly instructed
413. Field amplification injection in capillary electrophoresis (FACI) is a technique used to: (a) Increase the separation efficiency (b) Enhance the sensitivity by pre-concentrating the analytes at the injection end (c) Improve the resolution of large molecules (d) Allow for the analysis of hydrophobic compounds
414. The reporting limit (RL) is usually: (a) Lower than the method detection limit (MDL) (b) Equal to the MDL (c) Higher than the MDL and represents a level above which quantitative results can be stated with a higher degree of confidence (d) Independent of the MDL
415. X-ray emission spectroscopy (XES) involves analyzing the: (a) Absorption of X-rays as a function of energy (b) Emission of X-rays when a sample is bombarded with energetic particles (c) Diffraction of X-rays by a crystal lattice (d) Scattering of X-rays at small angles
416. Selected reaction monitoring (SRM) or multiple reaction monitoring (MRM) in tandem mass spectrometry is highly selective because it monitors: (a) All ions produced from the precursor ion (b) A specific precursor ion and a specific fragment ion (c) Only the most abundant ion in the mass spectrum (d) Ions with a very narrow mass-to-charge range
417. A Geiger-Müller counter is used to detect: (a) Alpha particles only (b) Beta particles only (c) Gamma rays only (d) Ionizing radiation
418. Total internal reflection fluorescence (TIRF) microscopy is often used to study: (a) The bulk properties of cells (b) Events occurring at or near the cell membrane (c) The internal structure of organelles (d) Highly scattering samples
419. Molecular beam epitaxy (MBE) is a technique similar to ABE used for: (a) Surface cleaning (b) Growing high-quality thin films in ultra-high vacuum (c) Analyzing the electronic structure of materials (d) Patterning surfaces at the microscale
420. Scanning near-field infrared microscopy (SNIM) allows for infrared spectroscopy with spatial resolution beyond the diffraction limit by using: (a) Synchrotron radiation (b) A sharp tip to probe the near-field (c) Time-resolved detection (d) Cryogenic temperatures
421. A Thiele tube is used for: (a) Sublimation of solids (b) Determining the melting point of a solid (c) Vacuum distillation of liquids (d) Refluxing reactions at controlled temperatures
422. A fume hood should be used when working with: (a) Non-toxic solids (b) Any volatile or hazardous chemicals (c) Biological samples only (d) Equipment that generates heat
423. Capillary electrochromatography (CEC) combines the principles of: (a) Gel electrophoresis and chromatography (b) Capillary electrophoresis and liquid chromatography, using electroosmotic flow as the driving force (c) Gas chromatography and mass spectrometry (d) Thin layer and column chromatography
424. The working calibration curve in quantitative analysis should: (a) Pass through the origin (b) Show a linear relationship between the signal and the analyte concentration over a defined range (c) Be non-linear to cover a wider range of concentrations (d) Only include a few data points
425. X-ray magnetic circular dichroism (XMCD) is used to study the: (a) Electronic band structure of non-magnetic materials (b) Magnetic properties of materials by measuring the difference in absorption of left- and right-circularly polarized X-rays (c) Topography of magnetic surfaces (d) Crystal structure of magnetic compounds
426. Atmospheric pressure chemical ionization (APCI) is an ionization technique used in mass spectrometry that is often coupled with: (a) Gas chromatography (b) Liquid chromatography (c) Capillary electrophoresis (d) Ion mobility spectrometry
427. A liquid scintillation counter is used to measure: (a) High-energy gamma radiation (b) Alpha and beta particles emitted by radionuclides mixed with a liquid scintillator (c) Neutrons (d) X-rays
428. Fluorescence correlation spectroscopy (FCS) is used to study: (a) The static distribution of fluorescent molecules (b) The dynamics of fluorescent molecules, such as diffusion and binding, by analyzing temporal fluctuations in fluorescence intensity (c) The spectral properties of fluorescent probes (d) The three-dimensional structure of proteins
429. Pulsed laser deposition (PLD) is a technique used for: (a) Etching materials with high precision (b) Growing thin films by ablating a target material with a pulsed laser (c) Analyzing the elemental composition of surfaces (d) Measuring the optical properties of thin films
430. Scanning near-field Raman microscopy (SNORM) combines near-field microscopy with Raman spectroscopy to achieve: (a) High spectral resolution (b) Sub-diffraction-limit spatial resolution in chemical imaging (c) Deep penetration into scattering samples (d) Time-resolved Raman spectra
431. A Craig tube is used for: (a) Small-scale countercurrent distribution (b) Determining the boiling point of a liquid (c) Sublimation of very small amounts of solid (d) Filtration of viscous solutions
432. Eating, drinking, or applying cosmetics is generally prohibited in the lab to prevent: (a) Distractions (b) Ingestion or absorption of hazardous materials (c) Clutter (d) Temperature fluctuations
433. Isoelectric focusing (IEF) is often used in proteomics to: (a) Determine the molecular weight of proteins (b) Separate proteins based on their isoelectric points as a first dimension in 2D gels (c) Analyze protein sequences (d) Study protein folding
434. A matrix blank in analytical chemistry is a sample: (a) Containing the analyte at a known concentration (b) Consisting of the sample matrix without the analyte (c) Used to zero the instrument (d) Prepared with distilled water only
435. X-ray standing wave (XSW) technique is used to study the: (a) Bulk crystal structure (b) Position of atoms at surfaces and interfaces with high precision (c) Magnetic domains within a material (d) Electronic band structure of thin films
436. Ion mobility spectrometry (IMS) separates ions based on their: (a) Mass-to-charge ratio in a vacuum (b) Mobility in a gas under an electric field (c) Binding affinity to a stationary phase (d) Size exclusion through a porous medium
437. A proportional counter is a type of radiation detector that produces a signal proportional to the: (a) Energy of the detected radiation (b) Number of incident photons (c) Intensity of the magnetic field (d) Temperature of the sample
438. Single-particle tracking (SPT) is used to study: (a) The average behavior of a population of molecules (b) The movement of individual molecules or particles within a system over time (c) The overall concentration of a substance (d) The equilibrium state of a reaction
439. Liquid phase epitaxy (LPE) is a method used for: (a) Etching semiconductor wafers (b) Growing epitaxial layers from a liquid solution (c) Analyzing the surface structure of liquids (d) Measuring the viscosity of liquid samples
440. Tip-enhanced Raman spectroscopy (TERS) combines AFM or STM with Raman spectroscopy to achieve: (a) High spectral resolution (b) Nanoscale spatial resolution in Raman imaging (c) Deep penetration into opaque materials (d) Time-resolved Raman measurements
441. A sublimator is used to: (a) Rapidly heat solids (b) Purify solids by sublimation (c) Mix powders uniformly (d) Measure the melting point of a solid
442. Before leaving the lab, you should always: (a) Leave your experiment running if it requires overnight processing (b) Clean your work area and wash your hands (c) Inform the person arriving next about your ongoing work (d) Store all chemicals in alphabetical order
443. Field-flow electrophoresis (FFE) separates particles based on their: (a) Size in a flow stream (b) Charge in an electric field applied perpendicular to the flow stream (c) Density in a centrifugal field (d) Affinity for a stationary matrix
444. The method of standard additions is used in quantitative analysis to: (a) Calibrate the instrument with pure standards (b) Minimize matrix effects by adding known amounts of the analyte to the sample (c) Simplify the sample preparation process (d) Increase the sensitivity of the method
445. X-ray tomography is used to obtain: (a) Surface images of materials (b) Three-dimensional images of the internal structure of objects (c) Elemental maps of a sample’s surface (d) Diffraction patterns from crystalline samples
446. Ambient ionization mass spectrometry techniques allow for the analysis of samples: (a) Only under high vacuum (b) Directly at atmospheric pressure without extensive sample preparation (c) Only if they are volatile (d) Only if they are non-polar
447. A cloud chamber is used to detect: (a) Electromagnetic radiation (b) Ionizing radiation by visualizing the paths of charged particles (c) Neutrinos (d) Gravitational waves
448. Single molecule fluorescence resonance energy transfer (smFRET) allows for the study of: (a) The average conformation of a population of molecules (b) Conformational changes and dynamics within individual molecules (c) The binding affinity between two types of molecules (d) The diffusion coefficient of a fluorescently labeled molecule
449. Focused ion beam (FIB) milling is used for: (a) High-resolution imaging of surfaces (b) Precise micro- and nanofabrication by sputtering material with a focused ion beam (c) Analyzing the elemental composition of a sample (d) Growing thin films with atomic layer precision
450. Scanning acoustic microscopy (SAM) is used to image: (a) The optical properties of surfaces (b) Subsurface features of materials by analyzing the reflection and transmission of ultrasonic waves (c) The magnetic domains within a sample (d) The thermal conductivity at the nanoscale

451. A micro-Kjeldahl apparatus is used for: (a) Digesting very small sample sizes for nitrogen determination (b) Rapid heating of small volumes (c) Precise titration of microliter volumes (d) Sublimation of microgram quantities of solids
452. When dealing with broken glassware in the lab, you should: (a) Pick it up with your bare hands if it’s a small piece (b) Use a brush and dustpan to collect it and dispose of it in a designated sharps container (c) Place it in the regular trash can after wrapping it in paper towels (d) Leave it for the cleaning staff
453. Sedimentation field flow fractionation (SdFFF) separates particles based on their: (a) Charge in an electric field (b) Size and density in a flow stream under a sedimentation field (c) Affinity for a stationary phase (d) Diffusion coefficients
454. Internal standards are used in quantitative analysis to: (a) Calibrate the instrument (b) Correct for matrix effects and variations in sample introduction or detector response (c) Increase the sensitivity of the method (d) Determine the limit of detection
455. X-ray computed tomography (X-ray CT) is used to create: (a) High-resolution surface images (b) Cross-sectional 3D images of an object from a series of 2D X-ray images taken at different angles (c) Elemental maps of a sample (d) Diffraction patterns of crystalline materials
456. Desorption electrospray ionization (DESI) is an ambient ionization technique used in mass spectrometry to analyze samples: (a) Only if they are in solution (b) Directly from surfaces at atmospheric pressure (c) After extensive chromatographic separation (d) Using high vacuum conditions
457. A gamma counter is specifically designed to measure: (a) Alpha radiation (b) Gamma radiation (c) Beta radiation (d) Neutron radiation
458. Single-molecule localization microscopy (SMLM) techniques like PALM and STORM achieve super-resolution by: (a) Using structured illumination (b) Exciting fluorophores with multiple photons (c) Precisely localizing individual fluorophores that are switched on sparsely in time (d) Depleting fluorescence at the edges of the excitation volume
459. Molecular layer epitaxy (MLE) is a vapor phase deposition technique used for: (a) Etching materials with atomic precision (b) Growing thin films by sequentially introducing different precursor vapors (c) Analyzing the composition of molecular beams (d) Measuring the thickness of molecular layers
460. Scanning Hall probe microscopy (SHPM) is used to map the: (a) Surface topography of materials (b) Magnetic field distribution above a sample surface with high spatial resolution (c) Electrical potential across a surface (d) Thermal conductivity at the nanoscale
461. A Claisen adapter is a piece of glassware used to: (a) Connect a flask to a condenser and a dropping funnel simultaneously (b) Measure precise volumes of liquids (c) Dry organic solvents (d) Perform vacuum filtration
462. Long-term storage of flammable liquids should be in: (a) A regular storage cabinet (b) A flammable liquid storage cabinet (c) A fume hood (d) A refrigerator
463. Capillary isoelectric focusing (cIEF) is often used for the analysis of: (a) Small organic molecules (b) Proteins and peptides based on their isoelectric points (c) Nucleic acids based on size (d) Lipids based on hydrophobicity
464. A performance check standard is used to: (a) Calibrate the instrument (b) Verify the stability and accuracy of the instrument during a sequence of analyses (c) Determine the limit of detection (d) Prepare the calibration curve
465. X-ray reflectivity (XRR) is a technique used to determine the: (a) Bulk crystal structure (b) Thickness and density of thin films and multilayers (c) Elemental composition of a surface (d) Electronic band structure
466. Direct analysis in real time (DART) is an ambient ionization technique for mass spectrometry that ionizes samples using: (a) A laser beam (b) A metastable gas stream (c) An electrospray plume (d) A chemical reaction on a surface
467. A neutron detector is used to measure: (a) Alpha particles (b) Neutrons (c) Beta particles (d) Gamma rays
468. Total internal reflection Raman microscopy combines TIRF with Raman spectroscopy to: (a) Enhance the Raman signal from the bulk (b) Obtain Raman spectra from a thin layer near the interface (c) Improve the spatial resolution of Raman imaging (d) Perform time-resolved Raman spectroscopy
469. Sputter deposition is a physical vapor deposition (PVD) technique used to: (a) Etch materials with high selectivity (b) Deposit thin films by bombarding a target with ions (c) Analyze the composition of sputtered particles (d) Grow single crystals from the vapor phase
470. Scanning electrochemical cell microscopy (SECCM) is used to study: (a) The optical properties of electrochemical interfaces (b) Localized electrochemical activity at surfaces with high spatial resolution (c) The magnetic behavior of electrochemical systems (d) The thermal gradients across electrochemical cells
471. A Vigreux column is used in distillation to: (a) Increase the rate of evaporation (b) Improve the separation of liquids with close boiling points (c) Prevent bumping (d) Collect the distillate more efficiently
472. Used culture plates should be: (a) Rinsed and reused (b) Autoclaved before disposal as biohazardous waste (c) Discarded directly into the regular trash (d) Soaked in bleach overnight
473. Free-flow electrophoresis (FFE) separates particles based on their: (a) Size in a laminar flow (b) Charge in a continuous flow under an electric field (c) Density in a gravitational field (d) Hydrophobicity in a buffer solution
474. The method of external standards involves: (a) Adding a known amount of analyte to the sample (b) Calibrating the instrument with solutions of known analyte concentration prepared separately from the sample (c) Using a substance similar to the analyte to correct for matrix effects (d) Analyzing the sample without any calibration
475. Synchrotron X-ray techniques often provide advantages such as: (a) Lower cost and simpler instrumentation (b) Higher intensity and tunability of the X-ray beam (c) Portability of the X-ray source (d) Reduced radiation hazards
476. Secondary electrospray ionization (SESI) is an ambient ionization technique for mass spectrometry that ionizes analytes by: (a) Direct laser ablation (b) Reaction with ions produced by a primary electrospray source (c) Thermal desorption (d) Chemical ionization at atmospheric pressure
477. A liquid scintillation analyzer is commonly used in: (a) X-ray diffraction studies (b) Radioisotope dating and biological assays involving beta emitters (c) Atomic absorption spectroscopy (d) Nuclear magnetic resonance imaging
478. Plasmon resonance microscopy is used to visualize: (a) Fluorescence from labeled molecules (b) Changes in refractive index near a metallic surface due to molecular binding (c) The topography of surfaces at atomic resolution (d) Magnetic domains
479. Molecular beam scattering (MBS) is a technique used to study: (a) The bulk properties of materials (b) Gas-surface interactions and chemical reactions at surfaces under well-defined conditions (c) The electronic structure of molecules in the gas phase (d) The diffusion of molecules in liquids
480. Scanning near-field optical microscopy (SNOM) or NSOM can overcome the diffraction limit by: (a) Using shorter wavelengths of light (b) Detecting light that has not diffracted using a probe in the near-field of the sample (c) Employing confocal optics with a very small pinhole (d) Using structured illumination patterns
481. A Soxhlet apparatus requires a solvent with a boiling point: (a) Much higher than the compound being extracted (b) Lower than the compound being extracted but high enough for reflux (c) Very close to the boiling point of the compound being extracted (d) That does not dissolve the compound being extracted
482. Working with sharps in the lab (e.g., needles, razor blades) requires: (a) Disposing of them in the regular trash if they were used for non-hazardous materials (b) Immediate disposal in a designated sharps container (c) Rinsing them with water before disposal (d) Recapping needles before disposal
483. Moving boundary electrophoresis separates molecules based on their: (a) Size through a gel matrix (b) Differential migration in a free solution under an electric field, forming distinct boundaries (c) Affinity for a stationary phase (d) Isoelectric point in a pH gradient
484. The slope of a calibration curve in quantitative analysis is related to the: (a) Limit of detection (b) Sensitivity of the method (c) Accuracy of the method (d) Precision of the method
485. X-ray crystallography is primarily used to determine the: (a) Elemental composition of a sample (b) Three-dimensional structure of crystalline materials (c) Surface morphology of solids (d) Electronic band structure of semiconductors
486. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) is a mass spectrometry technique well-suited for analyzing: (a) Small volatile organic compounds (b) Large biomolecules like proteins and polymers (c) Elemental composition of inorganic materials (d) Isotopic ratios
487. Cherenkov counting is a method used to detect: (a) Alpha particles (b) High-energy beta particles that travel faster than light in the medium (c) Gamma rays (d) Neutrons
488. Fluorescence lifetime imaging microscopy (FLIM) provides information about: (a) The intensity of fluorescence emission (b) The rate of decay of fluorescence, which can be sensitive to the microenvironment (c) The excitation and emission spectra of fluorophores (d) The movement of fluorescently labeled molecules
489. Chemical vapor deposition (CVD) is a technique used to: (a) Etch materials using chemical reactions (b) Deposit thin films by chemical reactions of gaseous precursors on a heated substrate (c) Analyze the composition of vapors (d) Grow single crystals from a melt
490. Scanning tunneling spectroscopy (STS) is used to measure the: (a) Topography of a surface (b) Electronic density of states at a specific point on a surface (c) Magnetic properties of a surface (d) Friction forces at the nanoscale
491. A Craig countercurrent distribution apparatus is used for: (a) High-efficiency distillation (b) Separating solutes based on their differential partitioning between two immiscible liquids over many transfer steps (c) Continuous extraction of solids (d) Precise temperature gradient crystallization
492. Unlabeled chemicals should: (a) Be disposed of immediately (b) Never be used; proper labeling is essential (c) Be identified by smelling them carefully (d) Be stored separately but can still be used
493. Pulsed-field gel electrophoresis (PFGE) is used to separate: (a) Small DNA fragments (b) Very large DNA molecules by periodically changing the direction of the electric field (c) RNA molecules based on their secondary structure (d) Proteins with similar molecular weights
494. The correlation coefficient (R2) of a calibration curve indicates the: (a) Accuracy of the calibration (b) Linearity of the calibration (c) Sensitivity of the method (d) Limit of detection
495. Powder X-ray diffraction (PXRD) is used to analyze: (a) Single crystals only (b) Polycrystalline materials to determine their phase composition and structure (c) Amorphous solids (d) Liquids
496. Chromatography-mass spectrometry (e.g., GC-MS, LC-MS) couples a separation technique with mass spectrometry to: (a) Increase the overall sensitivity (b) Identify and quantify separated analytes (c) Simplify sample preparation (d) Enhance the resolution of separation
497. Autoradiography is a technique used to visualize: (a) Fluorescently labeled molecules (b) Radioactively labeled substances in a sample (c) Enzyme activity through colorimetric reactions (d) Nucleic acid hybridization
498. Second harmonic generation (SHG) microscopy is a nonlinear optical technique used to image: (a) Fluorescently labeled structures (b) Non-centrosymmetric structures and interfaces based on their ability to generate photons with twice the frequency of the excitation light (c) Absorbing materials using transmitted light (d) Magnetic domains through magneto-optical effects
499. Focused electron beam induced deposition (FEBID) is a technique used for: (a) High-resolution electron microscopy (b) Direct-write nanofabrication by decomposing precursor molecules with a focused electron beam (c) Analyzing the energy loss of transmitted electrons (d) Imaging the magnetic properties of nanomaterials
500. Scanning ion microscopy (SIM) involves: (a) Scanning a light beam across a sample and detecting transmitted light (b) Bombarding a sample with a focused ion beam and detecting secondary ions or electrons (c) Scanning a sharp tip across a surface and measuring the force interaction (d) Analyzing the diffraction pattern of electrons scattered by a sample

Answer Key:

1. (d)
2. (b)
3. (c)
4. (c)
5. (b)
6. (b)
7. (c)
8. (c)
9. (b)
10. (c)
11. (c)
12. (c)
13. (c)
14. (d)
15. (c)
16. (b)
17. (c)
18. (b)
19. (b)
20. (c)
21. (c)
22. (c)
23. (c)
24. (b)
25. (c)
26. (c)
27. (a)
28. (b)
29. (b)
30. (c)
31. (c)
32. (b)
33. (c)
34. (c)
35. (b)
36. (a)
37. (b)
38. (c)
39. (b)
40. (b)
41. (b)
42. (c)
43. (c)
44. (c)
45. (c)
46. (c)
47. (c)
48. (a)
49. (b)
50. (b)
51. (a)
52. (b)
53. (c)
54. (c)
55. (b)
56. (c)
57. (c)
58. (b)
59. (b)
60. (c)
61. (b)
62. (c)
63. (c)
64. (b)
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66. (b)
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71. (b)
72. (b)
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74. (c)
75. (b)
76. (c)
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78. (b)
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83. (b)
84. (c)
85. (a)
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88. (a)
89. (b)
90. (a)
91. (b)
92. (b)
93. (c)
94. (c)
95. (c)
96. (c)
97. (c)
98. (b)
99. (b)
100. (b)
101. (b)
102. (c)
103. (c)
104. (c)
105. (b)
106. (b)
107. (a)
108. (c)
109. (b)
110. (c)
111. (a)
112. (c)
113. (c)
114. (d) 115

CONTINUE

115. (b)
116. (c)
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137. (d)
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