Chemistry Quiz 2

40 Questions

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Chemistry Quizzes & Trivia

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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

  • 2. 
    When plotting absorbance against concentration of a colored solution, which obey's 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

  • 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

  • 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

  • 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

  • 6. 
    • A. 

      0.80

    • B. 

      0.40

    • C. 

      0.20

    • D. 

      0.10

  • 7. 
    Light is passed through a solution with a light path of 2 cm and the absorbance is recorded as 0.40. If 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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 wavelngths 50% T occured. This type of test assesses the filter's
    • A. 

      Linearity

    • B. 

      Bandpass

    • C. 

      Calibration

    • D. 

      Absorbance Spectrum

  • 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

  • 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

  • 16. 
    Which of the following cannot be directly measured: 
    • A. 

      Transmitted light

    • B. 

      Incoming light

    • C. 

      Absorbed light

    • D. 

      None of the above

  • 17. 
    In regard to electromagnetic waves of radiant energy, the distance that a periodic wave propogates in one period of the distance between wave crests is referred to as: 
    • A. 

      Wavelength

    • B. 

      Modulation

    • C. 

      Amplitude

    • D. 

      Frequency

  • 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)

  • 19. 
    The most senstive device used in spectrophotometers for the conversion of polychromatic light to monochromatic is: 
    • A. 

      Diffraction grating

    • B. 

      Prism

    • C. 

      Glass filter

  • 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

  • 21. 
    • 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

  • 22. 
    Method requiring the measurement of absorbance in the UV region of the electromagnetic spectrum require that the sample cuvette be made of: 
    • A. 

      Glass

    • B. 

      Plastic

    • C. 

      Quartz

  • 23. 
    The units for molar absorptivity are:
    • A. 

      L/cm Mol

    • B. 

      Cm Mol/L

    • C. 

      Mol/L cm

    • D. 

      Unitless

  • 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

  • 25. 
    • 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

  • 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

  • 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

  • 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

  • 29. 
    • 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

  • 30. 
    • 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

  • 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

  • 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

  • 33. 
    Which of the following analytical systems does not require a light source?
    • A. 

      Atomic absorption

    • B. 

      Spectrophotometry

    • C. 

      Spectrofluorometry

    • D. 

      Luminometer

  • 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

  • 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

  • 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

  • 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

  • 38. 
    Two monochromators positioned at right angles is a chracteristic of which instrument? 
    • A. 

      Flame photometer

    • B. 

      Atomic Absorption Spectrophotometer

    • C. 

      Fluorometer

    • D. 

      Colorimeter

  • 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