Chemistry And Physics Quiz: Science Trivia!

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Chemistry And Physics Quiz: Science Trivia! - Quiz


Do you understand the difference between chemistry and physics? Physics is concerned with the entire universe down to the smallest measurement. Physics provides us with insights regarding space and time. Chemistry concentrates on how substances interact with each other and with energy. Chemistry also studies the properties of matter on a larger scale and the reactions of matter. If you are looking for a chemistry and physics quiz, you have come to the right place.


Questions and Answers
  • 1. 

    The visible region of the electromagnetic spectrum lies between wavelengths of ________. 

    • A.

      200-300

    • B.

      340-850

    • C.

      380-750

    • D.

      500-900

    Correct Answer
    C. 380-750
    Explanation
    The visible region of the electromagnetic spectrum refers to the range of wavelengths that can be detected by the human eye. This range is typically between 380 to 750 nanometers. Wavelengths shorter than 380 nm fall into the ultraviolet region and wavelengths longer than 750 nm fall into the infrared region. Therefore, the correct answer is 380-750.

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  • 2. 

    When plotting the absorbance against the concentration of a colored solution, which obeys Beer's Law, what procedure would be followed to obtain a straight-line graph with a positive slope?

    • A.

      Plot on semi-logarithmic graph paper with absorbance on semi-log axis

    • B.

      Plot on arithmetic graph paper

    • C.

      Plot on log-log paper

    • D.

      Convert to %T and plot on arithmetic graph paper

    • E.

      Plot on semi-logarithmic graph paper with concentration on semi-log axis

    Correct Answer
    B. Plot on arithmetic graph paper
    Explanation
    To obtain a straight-line graph with a positive slope when plotting the absorbance against the concentration of a colored solution that obeys Beer's Law, the procedure would be to plot on arithmetic graph paper. This is because Beer's Law states that there is a linear relationship between absorbance and concentration, meaning that as the concentration increases, the absorbance also increases. Plotting on arithmetic graph paper allows for a direct representation of this linear relationship.

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  • 3. 

    According to the Beer-Lambert Law, absorbance is: 

    • A.

      Inversely proportional to the concentration

    • B.

      Directly proportional to the concentration

    • C.

      Directly proportional to the transmittance

    • D.

      Directly proportional to the log of the concentration

    Correct Answer
    B. Directly proportional to the concentration
    Explanation
    According to the Beer-Lambert Law, absorbance is directly proportional to the concentration. This means that as the concentration of a substance increases, the absorbance of light by that substance also increases. This relationship can be explained by the fact that a higher concentration of molecules in a solution leads to more interactions with the incident light, resulting in greater absorption. Therefore, the higher the concentration, the higher the absorbance.

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  • 4. 

    In measuring the absorbance of a compound at 250 nanometers on a spectrophotometer, we have to use: 

    • A.

      An infra-red sensitive photocell

    • B.

      A tungsten lamp

    • C.

      A hydrogen discharge lamp

    • D.

      A mercury discharge lamp

    Correct Answer
    B. A tungsten lamp
    Explanation
    In order to measure the absorbance of a compound at 250 nanometers, a tungsten lamp is used. This is because tungsten lamps emit a broad spectrum of light, including visible and ultraviolet light. The compound being measured absorbs light at 250 nanometers, which falls within the ultraviolet range. Therefore, a tungsten lamp is suitable for providing the necessary light for the measurement.

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  • 5. 

    The intensity of scattered light from suspended particles?

    • A.

      Holds true in dilute solutions and small particle size

    • B.

      Holds true as particle size increases

    • C.

      Directly proportional to wavelength

    • D.

      All of the above

    Correct Answer
    A. Holds true in dilute solutions and small particle size
    Explanation
    The correct answer is "Holds true in dilute solutions and small particle size". This is because in dilute solutions, the particles are not densely packed, allowing more light to pass through and be scattered. Additionally, small particle size increases the likelihood of scattering as smaller particles have a higher surface area to volume ratio.

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  • 6. 

    Light is passed through a solution with a light path of 2 cm and the absorbance is recorded as 0.40. If the light is passed through the same solution at the same wavelength and the light path is reduced to 1 cm, the absorbance should be: 

    • A.

      0.80

    • B.

      0.40

    • C.

      0.20

    • D.

      0.10

    Correct Answer
    C. 0.20
    Explanation
    When the light path is reduced from 2 cm to 1 cm, the absorbance is expected to decrease. This is because absorbance is directly proportional to the light path length. As the light path is halved, the absorbance is also halved. Therefore, the absorbance should be 0.20 when the light path is reduced to 1 cm.

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  • 7. 

    Light is passed through a solution with a light path of 2 cm and the absorbance is recorded as 0.40. If the light is passed through the same solution at the same wavelength and the light path is reduced to 1 cm, the absorbance should be: 

    • A.

      0.80

    • B.

      0.40

    • C.

      0.20

    • D.

      0.10

    Correct Answer
    C. 0.20
    Explanation
    When the light path is reduced from 2 cm to 1 cm, the absorbance is expected to decrease because absorbance is directly proportional to the light path. As the light path is halved, the absorbance is also halved. Therefore, the absorbance should be 0.20, which is half of the initial absorbance of 0.40.

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  • 8. 

    Which of the following wavelengths of light would have the highest radiant energy?

    • A.

      200 nm

    • B.

      300 nm

    • C.

      400 nm

    • D.

      500 nm

    Correct Answer
    A. 200 nm
    Explanation
    The wavelength of light is inversely proportional to its energy. This means that shorter wavelengths have higher energy. Since 200 nm is the shortest wavelength among the given options, it would have the highest radiant energy.

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  • 9. 

    A component of a spectrophotometer that isolates radiant energy of a specific wavelength and excludes that of other wavelengths is called a(n):

    • A.

      Fluorometer

    • B.

      Incandescent lamp

    • C.

      Monochromator

    • D.

      Photomultiplier tube

    Correct Answer
    C. Monochromator
    Explanation
    A monochromator is a component of a spectrophotometer that isolates radiant energy of a specific wavelength and excludes that of other wavelengths. It achieves this by using a prism or diffraction grating to disperse the incoming light into its component wavelengths and then selecting a specific wavelength to pass through while blocking the others. This allows for precise control over the wavelength of light used in the spectrophotometer, enabling accurate measurements and analysis of samples based on their absorption or emission of light at specific wavelengths.

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  • 10. 

    To determine if the wavelength selector of a broad-bandpass spectrophotometer is actually isolating the desired wavelength, a __________ should be performed. 

    • A.

      Wavelength calibration with didymium filter

    • B.

      Linearity check with standard solutions

    • C.

      Spectral scan of a chromogen

    • D.

      Photometric zero adjustment

    Correct Answer
    A. Wavelength calibration with didymium filter
    Explanation
    To determine if the wavelength selector of a broad-bandpass spectrophotometer is actually isolating the desired wavelength, a wavelength calibration with a didymium filter should be performed. Didymium filters are commonly used for wavelength calibration as they have known absorption peaks at specific wavelengths. By comparing the measured absorption peaks with the known values, the accuracy of the spectrophotometer's wavelength selector can be verified. This calibration ensures that the instrument is correctly selecting the desired wavelength for accurate spectral measurements.

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  • 11. 

    A spectral absorbance curve may be used to: 

    • A.

      Find the wavelength of maximum absorbance

    • B.

      Select a wavelength best suited for measuring a compound

    • C.

      Identify an unknown compound by comparing its absorption spectra to that of a known compound

    • D.

      All of the above

    Correct Answer
    D. All of the above
    Explanation
    A spectral absorbance curve can be used to find the wavelength of maximum absorbance, as it shows the point at which the compound absorbs the most light. It can also be used to select a wavelength best suited for measuring a compound, as different compounds have different absorption characteristics. Additionally, by comparing the absorption spectra of an unknown compound to that of a known compound, it is possible to identify the unknown compound. Therefore, all of the given options are correct.

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  • 12. 

    A blank absorbance reading is used to: 

    • A.

      Compensate for variations in reagent interferences and its absorbance is subtracted from the absorbance of the net reaction with sample

    • B.

      Compensate for variations in reagent and sample interferences and its absorbance is subtracted from the absorbance of the net reaction with sample

    • C.

      Compensate for variations in sample interferences and its absorbance is subtracted from the absorbance of the net reaction with sample

    • D.

      Compensate for variations in reagent interferences and light source variation and its absorbance is subtracted from the absorbance of the net reaction with sample

    Correct Answer
    A. Compensate for variations in reagent interferences and its absorbance is subtracted from the absorbance of the net reaction with sample
    Explanation
    A blank absorbance reading is used to compensate for variations in reagent interferences. By subtracting the absorbance of the blank from the absorbance of the net reaction with the sample, any interference caused by the reagents can be eliminated, allowing for a more accurate measurement of the sample's absorbance.

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  • 13. 

    A monochromator's filter must be tested to determine whether it can isolate a specific part of the electromagnetic spectrum. Percent transmittance (%T) of light is plotted against wavelength. It is noted at which wavelengths 50% T occurred. This type of test assesses the filter's:

    • A.

      Linearity

    • B.

      Bandpass

    • C.

      Calibration

    • D.

      Absorbance Spectrum

    Correct Answer
    B. Bandpass
    Explanation
    In this question, the test being described involves plotting the percent transmittance (%T) of light against wavelength and noting the wavelengths at which 50% T occurred. This type of test is used to assess the filter's bandpass. Bandpass refers to the range of wavelengths that the filter allows to pass through while blocking others. By determining the wavelengths at which 50% T occurs, the test is evaluating the filter's ability to isolate a specific part of the electromagnetic spectrum, which is the definition of bandpass. Therefore, the correct answer is bandpass.

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  • 14. 

    Photometry is defined as: 

    • A.

      Measurement of light

    • B.

      A device used to measure light

    • C.

      The measurement of the intensity of light at selected wavelengths

    • D.

      All of the above

    Correct Answer
    A. Measurement of light
    Explanation
    Photometry is the branch of science that deals with the measurement of light. It involves quantifying the various properties of light such as intensity, brightness, and color. This can be done using specialized devices designed for measuring light, such as photometers or spectrophotometers. Additionally, photometry also includes the measurement of the intensity of light at specific wavelengths, which is crucial in various scientific and technological applications. Therefore, the correct answer is "Measurement of light" as it encompasses all the mentioned aspects of photometry.

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  • 15. 

    Monochromatic light is defined as:

    • A.

      The measurement of the intensity of light at selected wavelengths

    • B.

      Emission of light by molecules in an excited state produced by a chemical reaction or the absorption ionizing radiation

    • C.

      Electromagnetic radiation of one wavelength or extremely narrow wavelengths

    • D.

      Measurement of scattered light by suspended particles

    Correct Answer
    C. Electromagnetic radiation of one wavelength or extremely narrow wavelengths
    Explanation
    Monochromatic light refers to electromagnetic radiation that consists of only one wavelength or a very narrow range of wavelengths. This means that all the photons in monochromatic light have the same energy and frequency. It is often produced using lasers or filters that selectively transmit or emit light of a specific wavelength. Monochromatic light is used in various scientific and technological applications, such as spectroscopy, optical communication, and laser technology.

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  • 16. 

    Which of the following cannot be directly measured?

    • A.

      Transmitted light

    • B.

      Incoming light

    • C.

      Absorbed light

    • D.

      None of the above

    Correct Answer
    C. Absorbed light
    Explanation
    Absorbed light cannot be directly measured because it is the light energy that is absorbed by a material and converted into another form of energy, such as heat. Unlike transmitted light and incoming light, which can be measured using instruments like spectrophotometers or photodiodes, absorbed light cannot be directly quantified since it is no longer present in its original form. However, the effects of absorbed light can be indirectly measured through various techniques, such as measuring the increase in temperature or the resulting chemical reactions.

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  • 17. 

    In regard to electromagnetic waves of radiant energy, the distance that a periodic wave propagates in one period of the distance between wave crests is referred to as: 

    • A.

      Wavelength

    • B.

      Modulation

    • C.

      Amplitude

    • D.

      Frequency

    Correct Answer
    A. Wavelength
    Explanation
    The distance that a periodic wave propagates in one period of the distance between wave crests is referred to as wavelength. Wavelength is a fundamental property of electromagnetic waves and is defined as the distance between two consecutive crests or troughs of a wave. It is commonly represented by the symbol λ (lambda) and is measured in meters. Wavelength determines the color and energy of a wave, with shorter wavelengths corresponding to higher energy waves (such as gamma rays or X-rays) and longer wavelengths corresponding to lower energy waves (such as radio waves).

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  • 18. 

    What units of measurement are traditionally applied to radiant energy in the visible portion of the electromagnetic spectrum?

    • A.

      Milimeters (mm)

    • B.

      Centimeters (cm)

    • C.

      Micrometers (um)

    • D.

      Nanometers (nm)

    Correct Answer
    D. Nanometers (nm)
    Explanation
    Radiant energy in the visible portion of the electromagnetic spectrum is traditionally measured in nanometers (nm). This is because the wavelength of visible light falls within the range of approximately 400 to 700 nm. Nanometers are a suitable unit for measuring the small wavelengths of visible light, allowing for precise quantification of the energy carried by electromagnetic waves in this range.

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  • 19. 

    The most sensitive device used in spectrophotometers for the conversion of polychromatic light to monochromatic is: 

    • A.

      Diffraction grating

    • B.

      Prism

    • C.

      Glass filter

    Correct Answer
    A. Diffraction grating
    Explanation
    The diffraction grating is the most sensitive device used in spectrophotometers for the conversion of polychromatic light to monochromatic. This is because a diffraction grating is capable of separating light into its component wavelengths with high precision and accuracy. It does this by using a series of closely spaced parallel lines or grooves on a surface, which causes the light to diffract and create a spectrum. This allows for precise measurement and analysis of the different wavelengths present in the polychromatic light.

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  • 20. 

    When the _________, the rate of the reaction depends on the enzyme activity. When the _____________, the rate of the reaction depends on the substrate concentration

    • A.

      Substrate is in excess, enzyme is in excess

    • B.

      Enzyme is in excess, Substrate is in excess

    Correct Answer
    A. Substrate is in excess, enzyme is in excess
    Explanation
    When the substrate is in excess, it means that there is more substrate available than the enzyme can react with. In this case, the rate of the reaction depends on the enzyme activity because the enzyme is the limiting factor. The enzyme can only work as fast as it can convert the substrate into product. On the other hand, when the enzyme is in excess, it means that there is more enzyme available than the substrate. In this case, the rate of the reaction depends on the substrate concentration because the enzyme is not the limiting factor. The reaction rate can only increase if there is more substrate available for the enzyme to react with.

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  • 21. 

    Which of the following would have a negative impact on Beer's Law? 

    • A.

      Deviations in absorptivity coefficients at high concentrations (>0.01 M)due to electrostatic interactions between molecules in close proximity

    • B.

      Scattering of light due to particulates in the sample

    • C.

      Shifts in chemical equilibria as a function of concentration non-monochromatic radiation

    • D.

      Stray light

    • E.

      All of the above

    Correct Answer
    E. All of the above
    Explanation
    All of the factors mentioned in the options would have a negative impact on Beer's Law. Deviations in absorptivity coefficients at high concentrations due to electrostatic interactions between molecules in close proximity would affect the linearity of the relationship between absorbance and concentration. Scattering of light due to particulates in the sample would cause the absorption measurements to be inaccurate. Shifts in chemical equilibria as a function of concentration and non-monochromatic radiation would introduce errors in the measurements. Stray light would interfere with the accuracy of the absorbance measurements. Therefore, all of these factors would have a negative impact on Beer's Law.

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  • 22. 

    Method requiring the measurement of absorbance in the UV region of the electromagnetic spectrum requires that the sample cuvette be made of: 

    • A.

      Glass

    • B.

      Plastic

    • C.

      Quartz

    Correct Answer
    C. Quartz
    Explanation
    The method requiring the measurement of absorbance in the UV region of the electromagnetic spectrum requires the sample cuvette to be made of quartz. This is because quartz is transparent to UV light, allowing accurate measurements of absorbance in this region. Glass and plastic cuvettes are not transparent to UV light and would interfere with the measurement, leading to inaccurate results.

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  • 23. 

    The units for molar absorptivity are:

    • A.

      L/cm Mol

    • B.

      Cm Mol/L

    • C.

      Mol/L cm

    • D.

      Unitless

    Correct Answer
    A. L/cm Mol
    Explanation
    The molar absorptivity is a measure of how strongly a substance absorbs light at a specific wavelength. It is defined as the absorbance of a solution per unit path length and concentration. The units for molar absorptivity are L/cm Mol, which indicates that it is the ratio of concentration (in Moles per liter) to the path length (in centimeters) of the absorbing substance. This unit is commonly used in spectrophotometry to quantify the absorbance of a substance.

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  • 24. 

    Under specified conditions of pH and temperature, the international unit (IU) is defined as: 

    • A.

      The enzyme activity that catalyzes the conversion of 1 mol of substrate in 1 min under standard conditions

    • B.

      The enzyme activity that catalyzes the conversion of 1 mol of product in 1 min under standard conditions

    • C.

      The enzyme activity that catalyzes the conversion of 1 umol of substrate in 1 min under standard conditions

    • D.

      The enzyme activity that catalyzes the conversion of umol of product in 1 min under standard conditions

    Correct Answer
    C. The enzyme activity that catalyzes the conversion of 1 umol of substrate in 1 min under standard conditions
  • 25. 

    Which of the following statements about atomic absorption is not true: 

    • A.

      It requires that element to be measurement be brought to a non-ionized ground state

    • B.

      It uses a tungsten lamp as a light source

    • C.

      It uses a cathode made of the same element being measured

    • D.

      It measures the absorption of light

    Correct Answer
    B. It uses a tungsten lamp as a light source
    Explanation
    Atomic absorption spectroscopy (AAS) is a technique used to determine the concentration of elements in a sample. It works by measuring the absorption of light by the atoms of the element being analyzed. The light source used in AAS is not a tungsten lamp, but rather a hollow cathode lamp specific to the element being measured. The hollow cathode lamp emits light at a wavelength specific to the element, allowing for accurate measurement of its absorption. Therefore, the statement that AAS uses a tungsten lamp as a light source is not true.

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  • 26. 

    NADH peak absorbance occurs at ___________________ and NAD + has a peak absorbance at ________________.

    • A.

      290 and 380 nm

    • B.

      300 and 340 nm

    • C.

      340 and 250 nm

    • D.

      390 and 280 nm

    Correct Answer
    C. 340 and 250 nm
    Explanation
    NADH is a reduced form of NAD+ and it absorbs light at a different wavelength than NAD+. NADH has a peak absorbance at 340 nm, while NAD+ has a peak absorbance at 250 nm.

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  • 27. 

    In fluorometry, the emission radiation is always: 

    • A.

      Equal to excitation radiation

    • B.

      Of a longer wavelength than the excitation radiation

    • C.

      Of a shorter wavelength than the excitation radiation

    • D.

      More energetic than the excitation radiation

    Correct Answer
    B. Of a longer wavelength than the excitation radiation
    Explanation
    In fluorometry, the emission radiation is always of a longer wavelength than the excitation radiation. This is because when a molecule absorbs energy during excitation, it moves to a higher energy state. When it returns to its ground state, it releases the excess energy in the form of emission radiation. This emitted radiation has a longer wavelength because the energy difference between the excited state and ground state is inversely proportional to the wavelength of the emitted light. Therefore, the emission radiation in fluorometry is always of a longer wavelength than the excitation radiation.

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  • 28. 

    Interference resulting when two or more elements have emission spectra in adjacent or overlapping wavelengths is referred to as:

    • A.

      Self-absorption

    • B.

      Cationic Interference

    • C.

      Ionization Interference

    • D.

      Spectral Interference

    Correct Answer
    D. Spectral Interference
    Explanation
    Spectral interference refers to the interference that occurs when two or more elements have emission spectra in adjacent or overlapping wavelengths. This interference can lead to inaccurate measurements or difficulties in identifying and quantifying specific elements in a sample. It is important to account for and minimize spectral interference when analyzing samples using spectroscopic techniques.

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  • 29. 

    In atomic absorption spectroscopy, Which of the following statements is false: 

    • A.

      Flame is used to excite the element to a higher energy state

    • B.

      A Hallow-Cathode Lamp with a cathode made of the element to be analyzed is used to produce a wavelength of light specific for the material

    • C.

      This light is absorbed by the ground state atoms in the flame

    • D.

      There is a net decrease in the intensity of the beam

    Correct Answer
    A. Flame is used to excite the element to a higher energy state
    Explanation
    In atomic absorption spectroscopy, a flame is not used to excite the element to a higher energy state. Instead, a Hallow-Cathode Lamp with a cathode made of the element to be analyzed is used to produce a wavelength of light specific for the material. This light is then absorbed by the ground state atoms in the flame, resulting in a net decrease in the intensity of the beam.

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  • 30. 

    Which of the following statements best defines Luminescence?

    • A.

      The emission of light by a substance after absorption of excitation energy

    • B.

      Emission of light due to nonthermal process, a chemical reaction or the absorption of ionizing radiation

    • C.

      This light is absorbed by the ground state atoms

    • D.

      Emission of light requiring a light source

    Correct Answer
    B. Emission of light due to nonthermal process, a chemical reaction or the absorption of ionizing radiation
    Explanation
    Luminescence is the emission of light by a substance after absorption of excitation energy. This can occur through various processes such as a nonthermal process, a chemical reaction, or the absorption of ionizing radiation. The emitted light is a result of the excited state atoms returning to their ground state. It does not require a separate light source for the emission to occur.

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  • 31. 

    Quenching: 

    • A.

      Causes nonlinearity of a reaction response that occurs when the absorbance of a solution increases to greater than 2% of the exciting light

    • B.

      Involves fluorophores with small stokes shifts that have overlapping excitation and emission spectra and are susceptible to loss of detection because of background light scatter

    • C.

      Is related to the interaction of a fluorophore with a solvent or with a solute dissolved in the solvent that might result in a loss of fluorescence owing to energy transfer

    • D.

      Is caused by light scattering of proteins and other macromolecules in the sample matrix, which might cause unwanted background fluoroescence

    Correct Answer
    C. Is related to the interaction of a fluorophore with a solvent or with a solute dissolved in the solvent that might result in a loss of fluorescence owing to energy transfer
    Explanation
    Quenching refers to the interaction of a fluorophore with a solvent or solute dissolved in the solvent, which can lead to a loss of fluorescence due to energy transfer. This means that the fluorophore's ability to emit light is reduced or "quenched" when it interacts with certain molecules in its environment. This interaction can result in a decrease in the fluorescence intensity or a shift in the emission spectrum. Therefore, the correct answer explains that quenching is related to the interaction of a fluorophore with its surroundings, causing a loss of fluorescence.

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  • 32. 

    The amount of Rayleigh scattering that occurs to a beam of light is dependent upon?

    • A.

      The size of the particles and wavelength of the light

    • B.

      The size of particles, wavelength, and concentration

    • C.

      Size of particle and temperature

    • D.

      Sample pre-treatment

    Correct Answer
    B. The size of particles, wavelength, and concentration
    Explanation
    The amount of Rayleigh scattering that occurs to a beam of light is dependent upon the size of particles, wavelength, and concentration. Rayleigh scattering is the scattering of light by particles that are much smaller than the wavelength of the light. The intensity of scattering is inversely proportional to the fourth power of the wavelength, meaning that shorter wavelengths are scattered more. Additionally, the concentration of particles also affects the amount of scattering, as a higher concentration leads to more scattering. Therefore, all three factors - size of particles, wavelength, and concentration - play a role in determining the amount of Rayleigh scattering.

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  • 33. 

    Which of the following analytical systems does not require a light source?

    • A.

      Atomic absorption

    • B.

      Spectrophotometry

    • C.

      Spectrofluorometry

    • D.

      Luminometer

    Correct Answer
    D. Luminometer
    Explanation
    A luminometer is an analytical system that measures the amount of light emitted from a sample, such as luminescence or chemiluminescence. Unlike the other options, atomic absorption, spectrophotometry, and spectrofluorometry, which all require a light source to measure the absorption, transmission, or fluorescence of a sample, a luminometer does not need an external light source because it measures the light emitted directly from the sample itself. Therefore, a luminometer is the only option among the given choices that does not require a light source.

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  • 34. 

    In flame emission photometry, a photon of light with a wavelength specific for a given element is emitted when:

    • A.

      An orbital electron is raised to a higher energy state by incident light

    • B.

      The bonds of the molecule vibrate and release light

    • C.

      Thermal energy is absorbed by orbital electrons to a higher energy state and release energy when the orbital electrons return to the ground state

    • D.

      The element absorbs ultraviolet radiation and release energy at longer wavelengths

    Correct Answer
    C. Thermal energy is absorbed by orbital electrons to a higher energy state and release energy when the orbital electrons return to the ground state
    Explanation
    In flame emission photometry, thermal energy is absorbed by orbital electrons, causing them to move to a higher energy state. When these electrons return to their ground state, they release energy in the form of light with a specific wavelength. This process is known as emission, where the absorbed thermal energy is converted into light energy. This explanation aligns with the principles of flame emission photometry, where the emitted light is used to analyze and identify elements present in a sample.

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  • 35. 

    Which one of the following statements concerning turbidimetry is true?

    • A.

      It is the measure of the concentration of particles by measuring the amount of incident light absorbed by the particles

    • B.

      In a turbidimetric procedure, the measurement of light is made at right angles to the incident light

    • C.

      The intensity of the scattered light is inversely proportional to the number of particles in solution

    • D.

      In a turbidimetric measurement, light scattered particles in the solution is measured at 180 degrees from the incident light

    Correct Answer
    D. In a turbidimetric measurement, light scattered particles in the solution is measured at 180 degrees from the incident light
    Explanation
    In turbidimetry, the measurement of light is made at 180 degrees from the incident light. This means that the scattered light is measured in the opposite direction of the incident light. This measurement angle allows for a more accurate determination of the concentration of particles in the solution. By measuring the scattered light at 180 degrees, the turbidity of the solution can be determined, which is directly related to the concentration of particles present. Therefore, this statement is true.

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  • 36. 

    According to the equation  F= f I o abc 

    • A.

      Fluoroescence intensity is directly proportional to molar absorptivity and inversely related to fluorescence efficiency

    • B.

      Fluorescence intensity is directly related to the amount of emitted light

    • C.

      Fluorescence intensity is inversely proportional to concentration

    • D.

      Flourescence intensity decreases as molar absorptivity increases

    Correct Answer
    B. Fluorescence intensity is directly related to the amount of emitted light
    Explanation
    The correct answer is "Fluorescence intensity is directly related to the amount of emitted light." This means that as the amount of emitted light increases, the fluorescence intensity also increases. This relationship makes sense because fluorescence intensity is a measure of the brightness or strength of the fluorescence signal, and the brightness of the signal is directly related to the amount of light being emitted.

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  • 37. 

    Analytical sensitivity is related to: 

    • A.

      Lowest concentration of analyte that can be detected and accurately quantitated

    • B.

      The minimum cross reactivity with other analytes with similar structures

    • C.

      Highest concentration of analyte that can be detected and accurately quantitated

    • D.

      The highest cross reactivity with other analytes with similar structure

    Correct Answer
    A. Lowest concentration of analyte that can be detected and accurately quantitated
    Explanation
    Analytical sensitivity refers to the lowest concentration of analyte that can be detected and accurately quantitated. It determines the ability of an analytical method to detect and measure low levels of the analyte. A higher analytical sensitivity means that the method can detect lower concentrations of the analyte, making it more sensitive and reliable for quantitative analysis. Therefore, the correct answer is "lowest concentration of analyte that can be detected and accurately quantitated."

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  • 38. 

    Two monochromators positioned at right angles is a chracteristic of which instrument? 

    • A.

      Flame photometer

    • B.

      Atomic Absorption Spectrophotometer

    • C.

      Fluorometer

    • D.

      Colorimeter

    Correct Answer
    C. Fluorometer
    Explanation
    A fluorometer is an instrument used to measure the fluorescence emitted by a sample when it is excited by a specific wavelength of light. Two monochromators positioned at right angles are a characteristic of a fluorometer. This setup allows for the excitation light to be selected at one wavelength and the emitted fluorescence to be selected at another wavelength, ensuring accurate measurements of the fluorescence intensity.

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  • 39. 

    Which one of the following statements concerning turbidimetry is true?

    • A.

      It is the measure of the concentration of particles by measuring the amount of incident light absorbed by the particles

    • B.

      In a turbidimetric procedure, the measurement of light is made at right angles to the incident light

    • C.

      The intensity of the scattered light is inversely proportional to the number of particles in solution

    • D.

      In a turbidimetric measurement, light scattered particles in the solution is measured at 180 degrees from the incident light

    Correct Answer
    D. In a turbidimetric measurement, light scattered particles in the solution is measured at 180 degrees from the incident light
    Explanation
    In turbidimetry, the measurement of light scattered by particles in a solution is made at 180 degrees from the incident light. This means that the detector is positioned directly opposite the light source, allowing for accurate measurement of the scattered light. This method is commonly used to determine the concentration of particles in a solution, as the intensity of the scattered light is directly proportional to the number of particles present.

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Quiz Review Timeline +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Mar 22, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Apr 23, 2012
    Quiz Created by
    J1_black
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