ch15-ques-2013

Chapter Fifteen Topic: Spectroscopy Section: 15.1 Difficulty Level: Easy

1. Which of the following is not true about electromagnetic radiation? A) frequency is directly proportional to wavelength B) frequency is directly proportional to energy C) frequency is inversely proportional to wavelength D) wavelength is inversely proportional to energy E) none of these

Ans: A Topic: Spectroscopy Section: 15.1 Difficulty Level: Easy

2. Which of the following electromagnetic radiation has the highest energy? A) UV B) X-ray C) IR D) microwave E) visible

Ans: B Topic: Spectroscopy Section: 15.1 Difficulty Level: Easy

3. Which of the following electromagnetic radiation has the longest wavelength? A) UV B) X-ray C) IR D) microwave E) visible

Ans: D Topic: Spectroscopy Section: 15.1 Difficulty Level: Easy

4. Which of the following electromagnetic radiation has the highest frequency? A) UV B) X-ray C) IR D) microwave E) visible

Ans: B Topic: Spectroscopy Section: 15.1 Difficulty Level: Medium

5. Arrange the following electromagnetic radiation in decreasing (highest to lowest) order of frequency.

IR UV

I ΙΙ III IV V

microwave γ-rays visible

A) V>III>IV>II>I B) II>V>III>IV>I C) I>IV>III>V>II D) V>II>IV>III>I E) II>IV>V>III>I

Ans: B Topic: Spectroscopy Section: 15.1 Difficulty Level: Easy

6. Which of the following information is primarily obtained from infrared spectroscopy? A) arrangement of carbon and hydrogen atoms in a compound B) molecular weight of a compound C) conjugated π system present in a compound D) functional groups present in a compound E) all of these

Ans: D Topic: Infrared Spectroscopy Section: 15.2 Difficulty Level: Easy

7. Absorption of _______radiation results in vibrational excitation of the bonds in a compound.

A) UV B) Microwave C) IR D) Visible E) x-ray

Ans: C Topic: Infrared Spectroscopy Section: 15.2 Difficulty Level: Easy

8. Which of the following vibrations are observed in IR spectroscopy? A) stetching B) rotational C) bending D) A & B E) A & C

Ans: E Topic: Infrared Spectroscopy Section: 15.2 Difficulty Level: Easy

9. Which of the following is currently used to indicate the location of a signal on an IR spectrum?

A) wavelength B) wavenumber C) frequency D) A & B E) all of these

Ans: B Topic: Infrared Spectroscopy Section: 15.2 Difficulty Level: Easy

10. Which of the following are units for wavenumber in IR spectroscopy? A) cm—1

B) cm C) J.s—1

D) mm E) none of these

Ans: A

Topic: Signal Characteristics Section: 15.3 Difficulty Level: Easy

11. Which of the following corresponds to the functional group region on an IR spectrum? A) 1500-4000cm—1

B) 400-4000cm—1 C) 400-1500cm—1

D) 1500-2500cm—1 E) none of these

Ans: A Topic: Signal Characteristics Section: 15.3 Difficulty Level: Easy

12. Which of the following corresponds to the fingerprint region on an IR spectrum? A) 1500-4000cm—1

B) 400-4000cm—1 C) 400-1500cm—1

D) 1500-2500cm—1 E) none of these

Ans: C Topic: Signal Characteristics Section: 15.3 Difficulty Level: Medium

13. Which of the following statement(s) is(are) true about the frequency of a stretching vibration according to Hook’s law?

A) it is directly proportional to strength of the bond & the reduced mass

B) it is inversely proportional to strength of the bond & the reduced mass C) it is directly proportional to strength of the bond

D) it is inversely proportional to the reduced mass E) C & D

Ans: E Topic: Signal Characteristics Section: 15.3 Difficulty Level: Easy

14. Rank the indicated bonds in decreasing (highest to lowest) order of wavenumber.

II

III

H

HH

I

A) III>II>I

B) I>II>III C) II>I>III

D) III>I>II E) none of these

Ans: B Topic: Signal Characteristics Section: 15.3 Difficulty Level: Easy


II

III

OH

H

NH

IH

A) III>II>I



Ans: D Topic: Signal Characteristics Section: 15.3 Difficulty Level: Easy


II III

NH

I

O

A) III>II>I



Ans: D Topic: Signal Characteristics Section: 15.3 Difficulty Level: Medium

17. Which one of the following compounds will have the lowest wavenumber for carbonyl absorption?

O O O O O

I II III IV V

A) I

B) II C) III

D) IV E) V


18. Which one of the following compounds will have the lowest wavenumber for carbonyl absorption?

I II III IV

O O O NH2 O

V

O

O

A) I

B) II C) III

D) IV E) V


19. Which one of the following compounds will have the highest wavenumber for C=C absorption?

I II III IV V A) I

B) II C) III

D) IV E) V

Ans: C Topic: Signal Characteristics Section: 15.3 Difficulty Level: Hard

20. Which of the following compounds will have the highest wavenumber for carbonyl absorption?

O

O

O

O

O

O

I II III A) I

B) II C) III

D) II & III Ans: C

Topic: Signal Characteristics Section: 15.3 Difficulty Level: Medium

21. Arrange the indicated bonds in decreasing (highest to lowest) order of wavenumber.

I

IIIII

IV

OV

O

O

CN

H

A) I>V>II>IV>III

B) IV>II>I>V>III C) II>I>V>III>IV

D) IV>I>V>II>III E) IV>II>V>I>III

Ans: E Topic: Signal Characteristics Section: 15.4 Difficulty Level: Medium

22. Which of the following statement(s) is(are) true for an IR-active bond?

A) the bond must be symmetrical

B) it must change bond length C) it must change bond angle

D) it must change bond dipole E) all of these


23. Which of the following bonds is IR inactive?

IVIIIII

CH3CH2 C C H

I

CH3CH2 C C CH2CH3

A) I

B) II C) III

D) I & IV E) I & III


24. Which of the following bonds would produce the weakest absorption?

A) C=C

B) O—H C) C=O

D) sp3C—H E) A & D

Ans: A Topic: Signal Characteristics Section: 15.4 Difficulty Level: Medium

25. Which of the following bonds would produce the strongest absorption?

A) C=N

B) C≡C C) C=O

D) sp2C—H E) C—O


26. 3-hexyne does not show absorption in the range of 2000-2200 cm—1, whereas 1-hexyne does. Which of the following explains the reason for this absence of absorption for 3-hexyne?

A) it is a symmetrical compound

B) there is no change in bond dipole C) there is no bond dipole

D) it is an unsymmetrical compound E) A, B & C


27. Which of the following alkene groups will produce the strongest signal?

F Cl BrI II III IV

A) I

B) II C) III

D) IV Ans: A


28. Diluted alcohols show a _____absorption around 3600cm-1, due to _____.

A) sharp, hydrogen bonding

B) broad, hydrogen bonding C) sharp, absence of hydrogen bonding

D) broad, absence of hydrogen bonding Ans: C


29. Concentrated alcohols show a _____absorption in the region of 3200-3600cm-1, due to _____.

A) sharp, hydrogen bonding

B) broad, hydrogen bonding C) sharp, polarity

D) broad, polarity Ans: B


30. Carboxylic acids show a very broad absorption for the OH compared to alcohols, because they can form a ______.

A) dimer

B) polymer C) trimer

D) tetramer Ans: A


31. Primary amines show two medium absorption bands around 3400 cm-1, due to _______.

A) symmetric stretching

B) asymmetric stretching C) both symmetric and asymmetric stretching

D) hydrogen bonding Ans: C


32. How can you distinguish between cyclohexanol and cyclohexanecarboxylic acid using IR spectroscopy?

OH

OH

O

Cyclohexanecarboxylic acidCyclohexanol Ans: The OH absorption for the carboxylic acid is much broader than the alcoholic OH

and it will also show absorption for carbonyl group. Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Medium

33. Which of the following compounds will show a broad absorption around 3300 cm-1 and at 1650 cm-1?

OH O O OH

I II III IV

OOH

V A) I

B) II C) III

D) IV E) V

Ans: D Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Medium

34. Which of the following compounds will show a sharp absorption at 3300 cm-1 and at 2150 cm-1?

I II III IV

CN

A) I

B) II C) III

D) IV E) none of these

Ans: A Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Medium

35. Which of the following compounds will show two absorptions at 2600 cm-1 and at 2700 cm-1 along with the carbonyl absorption?

I II III IV

O

O

O

NH2

O

H

O

A) I

B) II C) III



36. Which of the following compounds will show absorption at 2250 cm-1?

I II III IV

NH2 NH

NC

N

A) I

B) II C) III


Ans: D

Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Medium

37. Which of the following compounds will have the lowest wavenumber for carbonyl absorption? O Cl O H O NH2 O OH O O

I II III IV V

A) I

B) II C) III

D) IV E) V

Ans: C Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Medium

38. Which of the following is true about the IR spectrum of the following compound?

Cl

O

A) absorptions at 1720 cm-1 & 2150 cm-1 B) absorptions at 1800 cm-1 & 2150 cm-1 C) absorptions at 1720 cm-1 & 2250 cm-1

D) absorptions at 1800 cm-1 & 2250 cm-1 E) absorptions at 1650 cm-1 & 2150 cm-1

Ans: B Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Medium

39. Which of the following compounds will show absorptions at 1640 cm-1, 2950 cm-1 and 3050 cm-1 on the IR spectrum?

O

O OH

I II III IV V

A) I B) II C) III D) IV E) V


40. A compound with molecular formula C6H10O, shows absorptions at 1720 cm-1 and at 2980 cm-1 on the IR spectrum. Propose a possible structure for this compound. Ans:

O


41. A compound with molecular formula C3H9N, shows absorptions at 3400 cm-1 (two), 2980 cm-1 and at 1100 cm-1 on the IR spectrum. Propose a possible structure for this compound. Ans: CH3CH2CH2NH2


42. A compound with molecular formula C4H8O2, shows absorptions at 2200-3600 cm-1 (broad), 1720 cm-1 and at 1200 cm-1 on the IR spectrum. Propose a possible structure for this compound. Ans:

OH

O

Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Hard

43. Which of the following compounds will have highest wavenumber for carbonyl absorption?

O

O

O

O

O

O

I IIIII

O

O

IV A) I

B) II C) III

D) IV Ans: B


44. Which of the following compounds will have two absorptions at 1820 cm-1 and 1740cm-1?

I IIIII IVO

O O

O

O

OH

O

NH2

O

Cl

O

V A) I

B) II C) III

D) IV E) V

Ans: D


45. Which one of the following compounds is consistent with the following IR spectrum?

SDBS: National Institute of Advanced Industrial Science and Technology

O

OHI II III IV

O OHOH

OH

O H

OHV

A) I

B) II C) III

D) IV E) V




O

NH2I II III IV

NH

N

ONH2

N

O

OH HNV

A) I

B) II C) III

D) IV E) V




I II III IV

OH

C

OH

N

OH

HO C

O

N A) I

B) II C) III

D) IV E) V

Ans: A Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Medium



H

OO

O

OH

I II III IVH

O

V

A) I

B) II C) III

D) IV E) V




OH

O

OH

OOH

I II III IV

OH

V

OH

A) I

B) II C) III

D) IV E) V

Ans: E Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Medium



NH2

CH3

NHCH3 NH2 NH2

CH3

CH3

N(CH3)2

I II III IV V

A) I

B) II C) III

D) IV E) V


51. For the following reaction, which of the following is consistent with the IR spectrum of the product?

CN

2. Η3Ο+

O H

1. DIBAH

A) absorption at 2250 cm-1 should disappear B) absorption at 3200-3400 cm-1 and 1720cm-1 should appear C) absorption at 2250 cm-1 should disappear, new absorption at 2600-2800 cm-1 and 1720

cm-1 should appear. D) absorption at 2250 cm-1 should disappear and absorption around 3400 cm-1 should

appear. E) none of these



H3O+

O

A) absorption at 2150 cm-1 should disappear B) absorption at 3300 cm-1 and 2150cm-1 should disappear C) absorption at 2250 cm-1 should disappear, new absorption at 3300 cm-1 should appear D) absorption at 1650 cm-1 should disappear and absorption at 3300 cm-1 should appear E) absorption at 3300 cm-1 and 2150cm-1 should disappear, a new absorption at 1720 cm-1

should appear

Ans: E Topic: Analyzing an IR spectrum Section: 15.6 Difficulty Level: Medium


1. NaH

OH OCH2CH3

2. CH3CH2Br A) absorption at 3200-3600 cm-1 should disappear B) absorption at 3200-3600 cm-1 and 1100 cm-1 should disappear C) absorption at 1100 cm-1 should disappear and absorption at 3100 cm-1 should appear D) absorption at 1650 cm-1 should disappear and absorption at 3300 cm-1 should appear. E) none of these

Ans: A Topic: Analyzing an IR spectrum Section: 15.7 Difficulty Level: Hard

54. Predict the product for the following reaction and explain how you will use IR spectroscopy to monitor the progress of the reaction. 1-pentyne

1. NaNH2

2. CH3CH2Br Ans: CH3CH2CH2C≡CCH2CH3

Absorptions for spC-H around 3300 cm-1 and C≡C around 2150 cm-1 should disappear from the product IR.


55. Predict the product for the following reaction and explain how you will use IR spectroscopy to monitor the progress of the reaction.

1. CH3CH2MgBr

2. H2O

O

Ans: HO

Absorptions for C=O around 1720 cm-1 would disappear and a new absorption for OH at 3200-3600 cm-1 would appear from the product IR

Topic: Mass Spectrometry Section: 15.8 Difficulty Level: Easy

56. Mass spectrometry is primarily used to determine: A) molecular formula of a compound B) molecular weight of a compound C) conjugation in a compound D) A & B E) A & C

Ans: D Topic: Mass Spectrometry Section: 15.8 Difficulty Level: Easy

57. Which of the following is initially produced when a compound is bombarded with high energy electrons?

A) anion B) free radical C) radical cation D) cation E) none of these

Ans: C Topic: Mass Spectrometry Section: 15.8 Difficulty Level: Easy

58. Which of the following is not true about the molecular ion in mass spectrometry? A) The molecular ion is produced by loss of one electron from the molecule. B) The mass of the molecular ion is equivalent to the mass of the molecule. C) The ion is produced by a loss of pair of electrons from the molecule. D) The molecular ion is often unstable and can undergo fragmentation. E) none of these

Ans: C Topic: Mass Spectrometry Section: 15.8 Difficulty Level: Easy

59. Which of the following is always true about the base peak in a mass spectrum? A) peak corresponding to molecular ion B) peak corresponding to the most abundant ion C) peak corresponding to lowest m/z D) A & C E) none of these

Ans: B Topic: Mass Spectrometry

Section: 15.8 Difficulty Level: Easy

60. The separation of ions in the mass spectrometer is done by their ______. A) electrons to protons ratio B) mass to neutrons ratio C) protons to neutrons ratio D) mass to charge ratio E) none of these

Ans: D Topic: Analyzing M+

• peak Section: 15.9 Difficulty Level: Easy

61. Which of the following is true about CH3CH3+•?

A) it is the parent ion of ethane B) it is a molecular ion of ethane with m/z =30 C) it is a fragment of propane D) A & B E) none of these


• peak Section: 15.9 Difficulty Level: Easy

62. Which of the m/z values corresponds to the base peak in the following mass spectrum?

A) 45 B) 44 C) 29 D) 15 E) none of these

Ans: C Topic: Analyzing M+

• peak Section: 15.9

Difficulty Level: Easy

63. Which of the m/z values correspond to the molecular ion peak in the following mass spectrum?


Ans: B Topic: Analyzing M+

• peak Section: 15.9 Difficulty Level: Medium

64. Which of the m/z values correspond to the molecular ion for the following compound? OH

A) 18 B) 82 C) 100 D) 102 E) 103



65. Which of the following compounds will have odd m/z value for the molecular ion?

H

O

H N

O

NN

Br

BrI II III IV

A) I B) II C) III D) IV E) none of these

Ans: B Topic: Analyzing M+


66. Which of the following is true about the molecular weight and the M+•-m/z value for the

following compound?

NH2

Cl

A) odd molecular weight, m/z-115 B) odd molecular weight, m/z-121 C) even molecular weight, m/z-96 D) even molecular weight, m/z-132 E) none of these

Ans: B Topic: Analyzing (M+1)+


67. Which of the following is true about the (M+1)+• peak on the mass spectrum of a

hydrocarbon?

A) it is the most abundant peak B) it is due to the 13C isotope of carbon C) it has a m/z value lower than the molecular ion D) it is useful in calculating number of carbon atoms E) B & D

Ans: E Topic: Analyzing (M+1)+


68. Which molecular formula is consistent with the following mass spectrum data? M+

• at m/z= 84, relative height=10.0%

(M+1)+• at m/z= 85, relative height=0.56%

A) C5H10O B) C5H8O C) C5H24 D) C6H12 E) C4H6O2






A) C4H10O B) C4H9N C) C5H12 D) C4H8O E) none of these

Ans: D Topic: Analyzing (M+1)+


70. Provide a molecular formula that is consistent with the following mass spectrum data. M+



Ans: C3H7NO

Topic: Analyzing (M+1)+

• peak Section: 15.10 Difficulty Level: Hard




Ans: C9H12O

Topic: Analyzing (M+1)+• peak

Section: 15.10 Difficulty Level: Hard




Ans: C8H9NO3

Topic: Analyzing (M+2)+


73. Compounds containing chlorine or bromine usually show a strong _____peak.

A) molecular ion B) base C) M+1 D) M+2 E) all of these

Ans: D Topic: Analyzing (M+2)+


74. Which of the following will produce M+• and (M+2)+

• peaks of equal intensity?

A) nitrogen B) chlorine C) bromine D) oxygen E) B & C

Ans: C Topic: Analyzing (M+2)+


75. Presence of bromine produces M+• and (M+2)+

• peaks of equal intensity on a mass spectrum because:

A) 81Br isotope has higher natural abundance than 79Br isotope B) 79Br and 81Br isotopes have almost equal natural abundance C) 79Br isotope has higher natural abundance than 81Br isotope D) none of these







A) C6H6 B) C3H7Cl C) C6H8 D) C6H9Cl E) none of these







A) C2H5Br B) C5H12Cl C) C8H12 D) C2H7Br E) none of these

Ans: A Topic: Analyzing (M+2)+


78. For which of the following compounds will the (M+2)+• peak intensity be around 25%

of the intensity of the molecular ion peak?

A) CH3CH2CH2Br B) CH3CH2CH2OH C) CH3CH2CH2Cl D) CH3CH2CH2NH2 E) none of these

Ans: C Topic: Analyzing (M+2)+


79. Which of the following mass spectra shows the presence of bromine in a compound?

I II

III IV Four spectra above: courtesy of SDBS: National Institute of Advanced Industrial Science and Technology

A) I B) II C) III D) IV E) none of these

Ans: A

Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

80. Which of the following compounds will produce a prominent (M-18) peak in the mass spectrum?

A) 2-methylheptane B) 1-heptanol C) heptanamine D) heptanal E) none of these

Ans: B Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

81. Which of the following compounds will produce a prominent (M-15) peak in the mass spectrum?

A) 2-methylheptane B) 1-heptanol C) heptanamine D) 1-chloroheptane E) none of these

Ans: A Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

82. Which of the following is not a prominent peak in the mass spectrum of 2-methyl-2-pentanol?

A) (M-15) B) (M-18) C) (M-29) D) (M-16) E) none of these

Ans: D Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

83. Which of the following compounds will have a prominent peak at (M-127)?

A) CH3CH2CH2I B) (CH3CH2)3CCH2Cl C) (CH3)3CCH2CH2Br D) (CH3)2CHCH(CH3)2 E) none of these

Ans: A Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

84. Which of the following compounds will have a base peak at m/z=43?

A) CH3CH2CH2CH2CH2CH3 B) (CH3CH2)2CHCH3 C) (CH3)3CCH2CH3 D) (CH3)2CHCH(CH3)2 E) none of these


85. Which of the following is the base peak in the mass spectrum of 2,2,4-trimethylpentane?



86. Which of the following is expected to be the base peak in the mass spectrum of CH3(CH2)4OH?


Ans: C Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

87. Which of the following is expected to be the base peak in the mass spectrum of 2-methyl-2-butanol?

A) 73 B) 55 C) 43 D) 31 E) 59

Ans: E Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

88. Which of the following is expected to be the base peak in the mass spectrum of CH3CH2NH2?


Ans: C Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

89. Provide the structures of the fragments that result when the molecular ion of 2-heptanone undergoes fragmentation via McLafferty rearrangement. Ans:

OH

+


90. Provide the structure of the major fragment that results when the molecular ion of (CH3)2CHCH2CH2NH2 undergoes fragmentation. Ans:

N

H

H Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

91. Provide the structure of the major fragment that results when the molecular ion of CH3CH2CH2CH2OH undergoes fragmentation via alpha cleavage. Ans: O

H Topic: Analyzing the fragments Section: 15.12 Difficulty Level: Medium

92. Which of the following is expected to be the base peak in the mass spectrum of pentanal?

CH3CH2CH2CH2CH

O

pentanal A) 29 B) 41 C) 44 D) 58 E) 86

Ans: C


93. Which one of the following compounds is consistent with the mass spectrum below?


A) CH3CH2CH(CH3)2 B) CH3CHOHCH2CH3 C) CH3CH2OCH2CH3 D) CH3CH2NHCH2CH3 E) none of these









Ans: A

Topic: High-resolution mass spectrometry Section: 15.13 Difficulty Level: Easy

96. High-resolution mass spectrometry is used to determine the _____ of a compound.

A) degree of unsaturation B) molecular formula C) molecular weight D) B & C E) none of these

Ans: B Topic: High-resolution mass spectrometry Section: 15.13 Difficulty Level: Medium

97. How will you distinguish between the following compounds using high-resolution mass spectrometry?

IIIO

O Cl

Ans: Compound I: m/z at 102.0678

Compound II: m/z at 102.0235 Topic: High-resolution mass spectrometry Section: 15.13 Difficulty Level: Medium

98. How will you distinguish between the following compounds using high-resolution mass spectrometry?

OH

I II Ans: Compound I: m/z at 98.0729

Compound II: m/z at 98.1092 Topic: Gas chromatography-mass spectrometry Section: 15.14 Difficulty Level: Medium

99. GC-mass spectrometry is used to find the _________ of each compound in a __________.

A) molecular formula, mixture of alkanes B) molecular weight, mixture of compounds C) molecular formula, mixture of compounds D) B & C E) none of these

Ans: B Topic: High-resolution mass spectrometry Section: 15.15 Difficulty Level: Medium

100. Electrospray ionization is used to obtain mass spectra of proteins because:

A) it allows for faster fragmentation of molecular ion B) the molecular ion usually does not undergo fragmentation C) it allows for slow fragmentation of molecular ion D) none of these

Ans: B Topic: Hydrogen deficiency index Section: 15.16 Difficulty Level: Easy

101. Calculate the degree of unsaturation for C9H11N.


Ans: D Topic: Hydrogen deficiency index Section: 15.16 Difficulty Level: Easy

102. Calculate the degree of unsaturation for C14H14N2O.

A) 4 B) 6 C) 8 D) 10 E) 9

Ans: E Topic: Hydrogen deficiency index Section: 15.16 Difficulty Level: Easy

103. Calculate the degree of unsaturation for C11H8ClBrO.

A) 4 B) 6 C) 7 D) 8 E) 10

Ans: C Topic: Hydrogen deficiency index Section: 15.16 Difficulty Level: Medium

104. Calculate the degree of unsaturation for C5H5Br2NO.

A) 4 B) 6 C) 2 D) 3 E) 7

Ans: D Topic: Hydrogen deficiency index Section: 15.16 Difficulty Level: Medium

105. Which of the following compounds have the same degree of unsaturation? C8H10BrIOC5H5Br2NO C6H5Br

I IIIIIC9H11NO

IV A) I & II B) I & III C) III & IV D) II & III E) none of these

Ans: B Topic: Hydrogen deficiency index Section: 15.16 Difficulty Level: Medium

106. Propose a possible structure for a compound with molecular formula C6H5Br Ans: Br

Topic: Hydrogen deficiency index Section: 15.16 Difficulty Level: Medium

107. Propose all possible structures for a compound with molecular formula C4H9N that shows two medium absorptions at 3400 cm-1 and no absorption in the range of 1600-1800 cm-1 in its IR spectrum. Ans: NH2NH2


108. Propose possible structure(s) for a compound with molecular formula C4H7N that shows absorption at 2250 cm-1 in its IR spectrum. Ans: CH3CH2CH2C≡N


109. Propose a possible structure for a compound with molecular formula C5H8O2 that shows

absorption at 1720 cm-1 and no absorption in the range of 1500-1700 cm-1 or 2600-2800 cm-1 in its IR spectrum. Ans: O O

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