1.2

1. 1Of the following compounds, which best matches the given IR spectrum?

   

   1. AI
   2. BII
   3. CIII
   4. DIV
2. 2Which of the following compounds gives this mass spectrum?

   

   1. AI
   2. BII
   3. CIII
   4. DIV
3. 3The concentration of an alcohol can be selected such that both a broad signal and a narrow signal appear simultaneously. In such cases, the broad signal is always to the right of the narrow signal, never to the left. Choose a correct explanation.
   

   1. AThe presence of hydrogen bonding results in a broad signal of the O-H stretching and it lowers the bond strength of the O-H bonds (because each hydrogen atom is slightly pulled away from the oxygen to which it is connected). A longer bond length (albeit temporary) corresponds with a weaker bond and hence, a lower wavenumber.
   2. BThe presence of hydrogen bonding results in a broad signal of the O-H stretching and it lowers the bond strength of the O-H bonds (because each hydrogen atom is slightly pulled away from the oxygen to which it is connected). A longer bond length (albeit temporary) corresponds with a weaker bond and hence, a higher wavenumber.
   3. CIn the presence of hydrogen bonding, the broad signal produced by C-O stretching contributes to a longer bond length (albeit temporary) and hence corresponds to a weaker bond and a lower wavenumber.
   4. DIn the presence of hydrogen bonding, the broad signal produced by C-H stretching contributes to a longer bond length (albeit temporary) and hence corresponds to a weaker bond and a lower wavenumber.
4. 4When placing electrons into degenerate orbitals, they are occupied singly and then paired up. Which rule is this?
   

   1. AHund's rule
   2. BBredt's rule
   3. CMarkovnikoff's rule
   4. DZaitsev's rule
5. 5Which of the following pairs are not related as resonance structures?

   1. AI
   2. BII
   3. CIII
   4. DIV
6. 6Evaluate the IR Spectrum below and choose which structure best fits the data

   

   1. AA
   2. BB
   3. CC
   4. DD
   5. EE
7. 7Ephedrine is a bronchodilator and decongestant obtained from the Chinese plant Ephedra sinica (Drug Test Anal 2018, 10, 350-356). A concentrated solution of ephedrine gives an IR spectrum with a broad signal between 3200 and 3600 cm³, An IR spectrum of a dilute solution of ephedrine is very similar to the IR spectrum of the concentrated solution. That is, the broad signal between 3200 and 3600 om is not transformed into a narrow signal, as we might expect for a compound containing an OH group.

   

   1. AThe OH group in ephedrine can engage in asymmetric stretching, even in dilute solutions.
   2. BThe OH group in ephedrine can engage in symmetric stretching, even in dilute solutions.
   3. CThe OH group in ephedrine can engage in intramolecular hydrogen bonding even in dilute solutions.
   4. DThe OH group in ephedrine can engage in vibrational excitation, even in dilute solutions.
8. 8The mass spectrum of an unknown hydrocarbon ohibits an (M+1) peak that is 10% as tall as the molecular lon peak. Select from the options below the number of carbon atoms in the unknown compound
   

   1. A10
   2. B11
   3. C8
   4. D9
9. 9Select the correct compound for the following spectrum

   

   1. AI
   2. BII
   3. CIII
   4. DIV
10. 10Choose the correct compound for the given IR spectrum

    

    1. AA
    2. BB
    3. CC
    4. DD
    5. EE
    6. FF

11. 11Which types of electromagnetic radiation shown has the longest wavelength?

    1. AUV
    2. BX-ray
    3. CIR
    4. DMicrowave
    5. Evisible
12. 12Arrange the given types of electromagnetic radiation in decreasing order of wavelength (from highest to lowest)

    

    1. AV > III > IV > II > I
    2. BII > V > III > IV > I
    3. CI > IV > III > V > II
    4. DV > II > IV > III > I
    5. EII > IV > V > III > I
13. 13Which of the given vibrations are observed in IR spectroscopy?

    1. AA. Stretching
    2. BB. Rotational
    3. CC. Bending
    4. DD. A and B.
    5. EE. A and C.
14. 14Which of the choices given are units of wavenumber in IR spectroscopy?

    1. Acm^-1
    2. Bcm
    3. CJ-s^-1
    4. Dmm
    5. EJ-s
15. 15Which of the given statement(s) is/are) true about the frequency of a stretching vibration according to Hooke's law?
    

    1. Ait is directly proportional to strength of the bond and the reduced mass
    2. Bit is inversely proportional to strength of the bond and the reduced mass
    3. CIt is directly proportional to strength of the bond and inversely proportional to the reduced mass
    4. Dit is inversely proportional to the strength of the bond and proportional to the reduced mass
    5. Eit is not related to either the strength of the bond or the reduced mass
16. 16Which of the given compounds has the lowest wave number for its carbonyl absorpotion?

    

    1. AI
    2. BII
    3. CIII
    4. DIV
    5. EV
17. 17Which of the given statement(s) is (are) true for an IR-active bond?

    1. Athe bond must be symmetrical
    2. Ba vibration must result in a change of bond length
    3. Ca vibration must result in a change of bond angle
    4. Da vibration must result in a change of bond dipole
    5. Ea vibration must result in a change of isotope
18. 183-Hexyne does not show absorption in the range of 2000-2200 cm, whereas 1-hexyne does. What is a reasonable explanation for 3 hexyne's absence of absorption?
    

    1. AA. It is a symmetrical compound
    2. BB. There is no change in bond dipole
    3. CC. There is no bond dipole
    4. DD. It is an unsymmetrical compound
    5. EE. A, B, and C.
19. 19Concentrated alcohols show a ________ absorption in the region of 3200-3600 cm³ due to_______
    
    

    1. Asharp, hydrogen bonding
    2. Bbroad, hydrogen bonding
    3. Csharp, polarity
    4. Dbroad, polarity
20. 20Which of the given compounds shows an absorption at 2250 cm^-1?

    

    1. AI
    2. BII
    3. CIII
    4. DIV
    5. EV
21. 21A compound with molecular formula C₂HN, shows absorptions at 3400 cm (two), 2980 cm¹ and at 1100 cm¹ on the IR spectrum. Propose a possible structure for this compound
    
    

    1. AA. CH3CH2CH2NH2
    2. BB. (CH3)2CHNH2
    3. CC. CH3NHCH2CH3
    4. DD. A AND B
    5. EE. A AND C
22. 22Which one of the given compounds is consistent with the IR spectrum shown?

    

    1. AI
    2. BII
    3. CIII
    4. DIV
    5. EV
23. 23Which one of the given compounds is consistent with the following IR spectrum?

    

    1. AI
    2. BII
    3. CIII
    4. DIV
    5. EV
24. 24For the given reaction which of the following changels) in the IR spectrum is consistent with conversion of the reactant to the product?
    

    1. Aabsorption at 3300-3400 cm should disappear
    2. Babsorption at 3300-3400 cm³ and 1100 cm should disappear
    3. Cabsorption at 1100 cm should disappear, a new absorption at 3100 cm³ should appear
    4. Dabsorption at 1650cm should disappear, a new absorption at 3300 cm³ should appear.
    5. Eabsorption at 3300-3400 cm should appear

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Test sobre 1.2, creado por Ela Kim el 23/09/2021.

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Ela Kim

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