Chem 221 exam 3 questions with correct detailed answers 100% pass

Which of the following is true? A. transition S1 to S0 is phosphorescence and the transition T1 to S0 is fluorescence, both radiational B. transition s1 to s0 is fluorescence and the transition T1 to s0 is phosphorescence, both radiational C. transition s1 to s0 is fluorescence and the transition T1 to s1 is phosphorescence, both are radtiational D. none of the above - Correct Answers B. transition s1 to s0 is fluorescence and the transition T1 to s0 is phosphorescence, both radiational The purpose of the blank is to A. cancel readings due to the color of the reagents B. account and subtract the absorbency due to imperfections in the cuvette C. cancel and subtract readings due to the absorbance of the reagents added to the analyte D. none of the above - Correct AnswersC. cancel and subtract readings due to the absorbance of the reagents added to the analyte A _____ lamp is used as a source of light in UV spectrophotometer, where as _____ lamp is used in case of atomic absorption spectroscopy A. deuterium arc, hollow cathode B. deuterium arc, tungsten C. hollow cathode, tungsten D. tungsten, hollow cathode - Correct AnswersA. deuterium arc, hollow cathode The purpose of the ashing step in graphite-furnace atomic absorption spectroscopy is to: A. vaporize metal atoms to be analyzed B. cause the metal to form carbides which are more volatile C. convert the graphite furnace to ash to avoid carbide formation D. burn off organic species that would interfere with elemental analysis - Correct AnswersD. burn off organic species that would interfere with elemental analysis How should the concentration of a colorless sample be determined? A. using a UV spectrophotometer B. using a VIS spectrophotometer C. Either a UV or VIS spectrophotometer D. using an indicator solution and pH paper - Correct AnswersA. using a UV spectrophotometer Self absorption can be expected in ____ at ______ analyte concentrations A. spectrophotometry, high B. flourometry, high C. atomic absorption, low D. flourometry, low - Correct AnswersB. flourometry, high The purpose of the flame in the ______ spectroscopy is to ______ A. atomic absorption, purify the sample B. atomic absorption, desolvate and atomize the analyte atoms in a sample C. ICP, excite the analyte atoms D. atomic absorption, ionize the analyte atoms - Correct AnswersB. atomic absorption, desolvate and atomize the analyte atoms in a sample Light is passed through a solution with a light path of 2.0 cm and the absorbance is recorded as 0.40 . If light is passed through the same solution as the same wavelength and the light path is reduced to 1.0 cm the absorbance should be : A. 0.80 B. 0.40 C. 0.20 D. 0.10 - Correct AnswersC. 0.20 Spectrophotometers use a monochromator containing a _________ to select the ________ assigned for measuring the aborbance of an analyte . - Correct AnswersGrating, wavelength Atomic emission originates from excited energy levels. Atoms in inductively coupled plasma are promoted to these higher levels by: A. an electric current from the RF generator B. absorbing light from the plasma C. collisions with other atoms and ions in the plasma D. tunneling - Correct AnswersC. collisions with other atoms and ions in the plasma Interference resulting when two or more elements have emission spectra in adjacent or overlapping wavelengths is referred to as _______ and can be minimized by ________. - Correct AnswersSpectral interference, using a different wavelength One of the main advantages of a furnace atomic absorption is that A. it requires only very small quantities of the sample B. it does not get hot like a flame C. it requires metal ions in aqueous solution D. All of the above - Correct AnswersA. it requires only very small quantities of the sample A solution has an absorbance of .62 at 595 nm. As you make the solution more and more dilute what happens to its absorbance at 595 nm? - Correct AnswersAbsorbency will decrease A 0.100 M aqueous solution of a nickel(ii) salt has a molar absobitivity of 2.95 (1/M *cm) at maximum wave length. What is the corresponding , if the path length of the solution cell used for the measurement is 1.00 cm? A. 0.340 B. 0.295 C. 2.95 D. none of the above - Correct AnswersB. 0.295 Compared to atomic absorption spectroscopy, inductively coupled plasma (ICP) has the advantage of providing A. analysis of organic compounds B. analysis of molecules C. simultaneous multi-element analysis D. all of the above - Correct AnswersC. simultaneous multi-element analysis A _____ lamp is used as the source of light in UV-spectrophotometer, whereas a _____ lamp is used in the case of atomic absorption spectroscopy. - Correct AnswersDeuterium arc, hollow cathode Two monochromators positioned at _____ degrees is a characteristic of _____________. - Correct Answers90 degrees, Fluorimeter In a scanning absorption spectrum, the dependent variable is _______ and the independent variable is ______. - Correct AnswersAbsorption, wavelength To establish a standard curve for a chemical, the spectrophotometer wavelength is set on which value? A. the lowest wavelength possible B. the wavelength at which the chemicals absorption value is the highest C. the wavelength at which the chemica