891. Why must the voltage supplied to a tungsten lamp be very stable?
A. Because if it wasn’t, the lamp would bum out
B. Because amount of energy the lamp emits is proportional to the fourth power of the operating voltage
C. Because the lamp will only function at a specific voltage
D. All of the above
892. Where does a carbonyl (C=0) stretch appear in an IR spectrum?
893. Which of the following components of a monochromator is the dispersing element?
A. The collimating lens
B. The entrance slit
C. The diffraction grating
D. None of these
894. A simple harmonic oscillator may absorb energy
A. at anytime.
B. when the frequencies match exactly
C. when the amplitudes are the same.
D. at no time.
895. UV-Vis spectroscopy of organic compounds is usually concerned with which electronic transition(s)?
A. σ → σ*
B. n → σ*
C. n → π* and π → π*
D. none of these
896. Vibrational spectroscopy is
A. a large mass on a weak spring
B. a flashlight through a prism and shake it
C. a class of spectroscopic techniques which analyzes molecular motions
D. an Infrared spectroscopy
897. Why are rotational transitions of little use to a spectroscopist?
A. Because the energy required to induce a rotational transition is so small that it cannot be measured
B. Because rotational transitions are extremely rare
C. Because, in liquids and solids, spectral lines corresponding to rotational transitions are broadened as the result of molecular collisions and other interactions
D. All of the above
898. Beer’s Law states that
A. absorbance is proportional to both the path length and concentration of the absorbing species
B. absorbance is proportional to the log of the concentration of the absorbing species
C. absorbance is equal to P0 / P
D. none of the above
899. What is the relationship between wavelength and wave number?
A. Wavenumber = 1 / wavelength in centimeters
B. Wavenumber – wavelength in nanometers = 1
C. Wavelength in nanometers x wavenumber = 1
D. None of the above
900. In the intersystem crossing
A. the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa)
B. a molecule converts its excess energy to light, and emits a photon
C. a molecule converts excess electronic energy to vibrational energy
D. all of the above