Deck 15: Infrared Spectroscopy and Mass Spectrometry

Question 1

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

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

Answer 1

III>I>II

Question 2

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 $\pi$ system present in a compound
D)functional groups present in a compound
E)all of these

Answer 2

functional groups present in a compound

Question 3

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

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

Answer 3

IV

Question 4

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

A)I
B)II
C)III
D)II & III

Question 5

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

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

Question 6

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

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

Question 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

Question 8

Which of the following electromagnetic radiation has the highest frequency?

A)UV
B)X-ray
C)IR
D)microwave
E)visible

Question 9

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

Question 10

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

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

Question 11

Which of the following vibrations are observed in IR spectroscopy?

A)stetching
B)rotational
C)bending
D)A & B
E)A & C

Question 12

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

Question 13

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

Question 14

Which of the following electromagnetic radiation has the highest energy?

A)UV
B)X-ray
C)IR
D)microwave
E)visible

Question 15

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

Question 16

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

Question 17

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

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

Question 18

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

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

Question 19

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

Question 20

Which of the following electromagnetic radiation has the longest wavelength?

A)UV
B)X-ray
C)IR
D)microwave
E)visible

Question 21

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

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

Question 22

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

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

Question 23

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

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

Question 24

Which of the following bonds would produce the strongest absorption?

A)C=N
B)C $\equiv$ C
C)C=O
D)sp²C-H
E)C—O

Question 25

Which of the following bonds is IR inactive?

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

Question 26

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

Question 27

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

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

Question 28

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

Question 29

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

Question 30

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

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

Question 31

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.

Question 32

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

Question 33

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

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

Question 34

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

Question 35

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

Question 36

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.

Question 37

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

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

Question 38

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

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

Question 39

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

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

Question 40

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

Question 41

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

Question 42

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

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

Question 43

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

Question 44

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

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

Question 45

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

Question 46

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

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

Question 47

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

Question 48

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

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

Question 49

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

Question 50

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

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

Question 51

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

Question 52

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

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

Question 53

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

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

Question 54

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

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

Question 55

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.

Question 56

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

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

Question 57

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

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

Question 58

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

Question 59

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

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

Question 60

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

Question 61

Provide a molecular formula that is consistent with the following mass spectrum data.
M^{+ •} at m/z= 136,relative height=65.6%
(M+1)^{+ •} at m/z= 137,relative height=6.2%

Question 62

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

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

Question 63

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

Question 64

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

Question 65

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

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

Question 66

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

Question 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

Question 68

Provide a molecular formula that is consistent with the following mass spectrum data.
M^{+ .} at m/z= 167,relative height=50.0%
(M+1)^{+ .} at m/z= 168,relative height=4.4%

Question 69

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

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

Question 70

Which molecular formula is consistent with the following mass spectrum data?
M^{+ •} at m/z= 108,relative height=61.5%
(M+1)^{+ •} at m/z= 109,relative height=1.5%
(M+2)^{+ •} at m/z= 110,relative height=61.3%

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

Question 71

Provide a molecular formula that is consistent with the following mass spectrum data.
M^{+ •} at m/z= 73,relative height=86.1%
(M+1)^{+ •} at m/z= 74,relative height=3.2%

Question 72

Which of the following is true about the molecular weight and the M^{+ •} -m/z value for the following compound?

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

Question 73

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

Question 74

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

Question 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

Question 76

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

Question 77

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

Question 78

Which molecular formula is consistent with the following mass spectrum data?
M^{+ •} at m/z= 78,relative height=23.5%
(M+1)^{+ •} at m/z= 79,relative height=0.78%
(M+2)^{+ •} at m/z= 80,relative height=7.5%

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

Question 79

Which molecular formula is consistent with the following mass spectrum data?
M^{+ •} at m/z= 72,relative height=73.0%
(M+1)^{+ •} at m/z= 73,relative height=3.3%

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

Question 80

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