12- Which of the following transitions is mostly occurred in phenyl chromophoric groups for UV-Vis light a.1111absorption? b. nn2 c. n d. nII 13- Excited atoms in vapor state can emit: a- Continuum spectra b. Line spectra c- Band spectra d- All of the above e- None of the above 14. fluorescence spectra. a- Resonance line b- Stokes shift b- Band broadening d- Emission spectrum 15- Molecular fluorescence is a two-step process; the second step is as follows: a. M+ heat hu b. M+huM c. MM+ heat d. MM+hv e. MM+hu 16- To determine Pb in a blood sample by AAS, you will need the following: a- Xenon arc lamp as special radiation source for blood b- Tungsten Lamp c- Pb hollow cathode lamp d- Helium gas 17. Calibration curve in spectrophotometry is a plot of: a- Absorbance versus concentration. b- Absorbance versus wavelength c- Transmitted light intensity versus concentration. d- % T versus wavelength 18- Select the wavelength range corresponding to UV-VIS region. a. 400800nm b. 200800nm c. 25m2.5m d. 2.5m1.0mm