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Questions on UV

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Questions and Discussion

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Questions on UV

  1. 1. Questions and Discussions
  2. 2. 1. UV-Vis. Spectroscopy of organic compounds is usually concerned with which electronic transition(s) a)n __> π* b)π __> π* c)n __> σ* d)σ __> σ* e)All the above
  3. 3. 2. Which of the following wavelength ranges is associated with UV spectroscopy? 1. 0.8 - 500µm 2. 400 - 100nm 3. 380 - 750nm 4. 0.01 - 10nm
  4. 4. 3. Which of the following compounds does not absorb light in the UV/visible spectrum? A)Aspirin B) Paracetamol C) Chloral hydrate D)Phenobarbitone
  5. 5. 4. A series of 3 colored glass plates of equal thickness are placed in a light beam. Each sheet absorbs one quarter of the light incident upon it. What is the intensity of the light transmitted by the third glass plate? A) 1.56% B) 42.19% C) 56.25% D) 75.00%
  6. 6. 5. Blue light in the visible region has a longer wave length A) IR radiation B) X-rays C) Microwaves D) Red light in the visible
  7. 7. 6. What is the molar absorptivity of a compound if a 4.4 X 10-5 molar solution has an absorbance of 0.105 when the path length is 1.0 cm? A)4.2 X 10-4 B) 1.0 X 108 C) 2.4 X 103 D)4.62 X 10-6
  8. 8. 7. The %transmittance of a sample is measured to be 34%. What will the absorbance be if the concentration is doubled? A. 0.94 B. 0.68 C. 0.23 D.0.17
  9. 9. 8. UV detector is used in one of the following methods A. Gas-Liquid chromatography B. High Performance liquid chromatography C. Size Exclusion chromatography D. Affinity Chromatography
  10. 10. 9. The colour of dilute solution of copper sulfate is light blue in colour, addition of _______ intensifies the colour and shift the λmax A. Chlorine B. Nitrogen C. Hydrogen D.Carbon di oxide
  11. 11. 10. Which of the following transitions is the highest energy transition? a) n __> π* b) π __> π* c) n __> σ* d) σ __> σ* e) All the above
  12. 12. 11. Which of the following alkenes would have the largest λmax ?
  13. 13. 12. Which of the following alkenes would have the largest λmax?
  14. 14. 13. What is the λmax for the following compound? Use the provided parameters for your calculation. A. 234 B. 244 C. 273 D. 278 E. 283
  15. 15. 14. What is the λmaxfor the following compound? Use the above parameters for your calculation. A. 229 nm B. 249 nm C. 254 nm D. 259 nm
  16. 16. 15. What is the X and Y axis in this graph?
  17. 17. 16. What is the relationship between Absorbance and Transmittance of a light through a sample in a Spectophotometer A. An increase in transmittance usually results in increase in absorbance B. An decrease in transmittance usually results in decrease in absorbance C. An increase in transmittance usually results in decrease in absorbance D. Transmittance and Absorbance should remain equal

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