Which of the following statements about fluorescence and phosphorescence is TRUE

Question

Which of the following statements about fluorescence and phosphorescence is TRUE? Fluorescence is slower than phosphorescence. Fluorescence is a radiation transition between the states of different multiplicities. The lifetime of a fluorescence state is of the order of seconds. The wavelength of the photon promoting excitation is shorter than the wavelength of the emitted photon. Arrange the following protons in order of increasing the chemical shift. The protons are indicated by an alpha symbol. 2, 3, 4, 5, 1 5, 2, 1, 3, 4 5, 2, 1, 4, 3 5, 1, 2, 4, 3 5, 1, 2, 3, 4 TRUE OR FALSE (7-11) Electronic transitions correspond to UV-Vis region of electromagnetic radiation. NMR spectroscopy is based on the interactions of electron spin with magnetic field. In NMR spectroscopy, the chemical shift of a proton increases with the shielding constant.

Explanation / Answer

5. Statements C.) and D.) are true

6. The correct order is C.) 5,2,1,4,3. The chemical shift is lowest for alkane, followed by alkyl halides where more electronegative the halide ion is (Cl > I) more is the deshielding effect. Then comes the aromatic proton which is deshielded by ring current and aldehyde proton exhibits highest chemical shift due paramagnetic effect.

7. True

8. True

9. False

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