MCQOPTIONS
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MCQOPTIONS
This section includes 19 Mcqs, each offering curated multiple-choice questions to sharpen your Organic Chemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A substance absorbs 2.0 x 1016 quanta or radiations per second and 0.002 mole of it reacts in 1200 seconds. What is the quantum yield or the reaction (N = 6.02 x 1023)? |
| A. | 50 |
| B. | 40 |
| C. | 80 |
| D. | 100 |
| Answer» B. 40 | |
| 2. |
Which of the following are the reactions in which molecules absorbing light do not themselves react but induce other molecules to react? |
| A. | Free radical reactions |
| B. | Chain reactions |
| C. | Reversible reactions |
| D. | Photosensitized reactions |
| Answer» E. | |
| 3. |
The quantum efficiency of a photochemical reaction is defined as _______ |
| A. | ratio of molecules decomposed in a given time to the number of quanta absorbed in the same time |
| B. | number of 11101ecules decomposed in a given time |
| C. | number or quanta absorbed percent time |
| D. | ratio of’ molecules decomposed in a given time to the number of quanta emitted in the same time |
| Answer» B. number of 11101ecules decomposed in a given time | |
| 4. |
Which of the following will result in deviation from Beer’s law? |
| A. | A, B and C |
| B. | B, C and D |
| C. | A, C and D |
| D. | A, B and DView Answer |
| Answer» B. B, C and D | |
| 5. |
A 0.1 M solution of compound A shows 50% transmittance when a cell of 1 cm width is used at λ1 nm. Another 0.1 M solution of compound B gives the optical density value of 0.1761 using 1cm cell at λ1 nm. What will be the transmittance of a solution that is simultaneously 0.1 M in A and 0.1 M in B using the same cell and at the same wave length? [log 1.301; log 1.4771; log 50 = 1.699]. |
| A. | 33.3% |
| B. | 50% |
| C. | 66.7% |
| D. | 70% |
| Answer» B. 50% | |
| 6. |
What are the appropriate reasons for the deviation from the Beer’s law among the following? |
| A. | A, B and D |
| B. | B, C and D |
| C. | A, C and D |
| D. | A, B and CView Answer |
| Answer» C. A, C and D | |
| 7. |
The molar extinction coefficient of B (MW = 180) is 4 x 103 L mol-1 cm-1. One-liter solution of C which contains 0.1358 g pharmaceutical preparation of B, shows an absorbance of 0.411 in a 1 cm quartz cell. What is the percentage (w/w) of B in the pharmaceutical preparation? |
| A. | 10.2 |
| B. | 13.60 |
| C. | 20.40 |
| D. | 29.12 |
| Answer» C. 20.40 | |
| 8. |
Which regions of the light radiations of the visible ultraviolet lying between – wavelength are chiefly concerned in bringing about photochemical reactions? |
| A. | 1000 Å and 2000 Å |
| B. | 1500 Å and 1000 Å |
| C. | 8000 Å and 2000 Å |
| D. | 19000 Å and 12,000 Å |
| Answer» D. 19000 Å and 12,000 Å | |
| 9. |
WHICH_OF_THE_FOLLOWING_ARE_THE_REACTIONS_IN_WHICH_MOLECULES_ABSORBING_LIGHT_DO_NOT_THEMSELVES_REACT_BUT_INDUCE_OTHER_MOLECULES_TO_REACT??$ |
| A. | Free radical reactions |
| B. | Chain reactions |
| C. | Reversible reactions |
| D. | Photosensitized reactions |
| Answer» E. | |
| 10. |
THE_QUANTUM_EFFICIENCY_OF_A_PHOTOCHEMICAL_REACTION_IS_DEFINED_AS________?$ |
| A. | ratio of molecules decomposed in a given time to the number of quanta absorbed in the same time |
| B. | number of 11101ecules decomposed in a given time |
| C. | number or quanta absorbed percent time |
| D. | ratio of’ molecules decomposed in a given time to the number of quanta emitted in the same time |
| Answer» B. number of 11101ecules decomposed in a given time | |
| 11. |
A substance absorbs 2.0 x 1016 quanta or radiations per second and 0.002 mole of it reacts in 1200 seconds. What is the quantum yield or the reaction (N = 6.02 x 1023)?$ |
| A. | 50 |
| B. | 40 |
| C. | 80 |
| D. | 100 |
| Answer» B. 40 | |
| 12. |
Which of the following will result in deviation from Beer’s law?# |
| A. | Change in a refractive index of medium |
| B. | Dissociation of analyte on dilution |
| C. | Polychromatic light |
| D. | Path length of cuvette |
| Answer» B. Dissociation of analyte on dilution | |
| 13. |
A 0.1 M solution of compound A shows 50% transmittance when a cell of 1 cm width is used at λ1 nm. Another 0.1 M solution of compound B gives the optical density value of 0.1761 using 1cm cell at λ1 nm. What will be the transmittance of a solution that is simultaneously 0.1 M in A and 0.1 M in B using the same cell and at the same wave length? [log 1.301; log 1.4771; log 50 = 1.699].$ |
| A. | 33.3% |
| B. | 50% |
| C. | 66.7% |
| D. | 70% |
| Answer» B. 50% | |
| 14. |
What are the appropriate reasons for the deviation from the Beer’s law among the following?$ |
| A. | Monochromaticity of light |
| B. | Very high concentration of analyte |
| C. | Association of analyte |
| D. | Dissociation of analyte |
| Answer» C. Association of analyte | |
| 15. |
The molar extinction coefficient of B (MW = 180) is 4 x 103 L mol-1 cm-1. One-liter solution of C which contains 0.1358 g pharmaceutical preparation of B, shows an absorbance of 0.411 in a 1 cm quartz cell. What is the percentage (w/w) of B in the pharmaceutical preparation? |
| A. | 10.20 |
| B. | 13.60 |
| C. | 20.40 |
| D. | 29.12 |
| Answer» C. 20.40 | |
| 16. |
Which of the following instruments is used to measure the energy of the monochromatic radiation most accurately? |
| A. | Photoelectric cell |
| B. | Thermopile |
| C. | The potential detector |
| D. | The chemical actinometer |
| Answer» C. The potential detector | |
| 17. |
Which regions of the light radiations of the visible ultraviolet lying between – wavelength are chiefly concerned in bringing about photochemical reactions?$ |
| A. | 1000 √Ö and 2000 √Ö |
| B. | 1500 √Ö and 1000 √Ö |
| C. | 8000 √Ö and 2000 √Ö |
| D. | 19000 √Ö and 12,000 √Ö |
| Answer» D. 19000 ‚Äö√†√∂‚àö√± and 12,000 ‚Äö√†√∂‚àö√± | |
| 18. |
Which of the following is an incorrect statement? |
| A. | First step in photochemistry is excited state (photoexcitation) |
| B. | Photochemical reactions are caused by absorption of ultraviolet only |
| C. | When a molecule or atom in the ground state (S<sub>0</sub>) absorbs light, one electron is excited to a higher orbital level |
| D. | it is possible for the excited state S<sub>1</sub> to undergo spin inversion |
| Answer» C. When a molecule or atom in the ground state (S<sub>0</sub>) absorbs light, one electron is excited to a higher orbital level | |
| 19. |
The fact that the fluorescence wavelength is often much longer than the irradiation wavelength (Stokes shift) is a consequence of which phenomenon? |
| A. | low extinction coefficients (Lambert-Beer law) |
| B. | vertical transitions (Kasha’s rule) |
| C. | high ISC rates (El Sayed rule) |
| D. | the Franck–Condon principle |
| Answer» E. | |