Exam code: 9701
Which of the following corresponds to the base peak in a mass spectrum?
The peak corresponding to the ion with lowest m/e.
The peak corresponding to the molecular ion.
The peak corresponding to any ion formed by the fragmentation of the molecule.
The peak corresponding to the most abundant ion.
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The diagram shows the structure of ricinoleic acid.
Which fragment would produce the tallest peak in the mass spectrum of ricinoleic acid at m/e = 55?
CH2CO2+
CH═CHCHOH+
C4H7+
COOH+
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In a mass spectrometer, the ions are separated.
Which of the following species will be deflected to the greatest extent?
37Na+
35Na+
37Na
35Na2+
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A sample of silicon contains the following isotopes
Isotope | Percentage abundance |
28Si | 81.21 |
29Si | 14.10 |
30Si | 4.69 |
What is the relative atomic mass of silicon in this sample, to 1dp?
29.8
29.0
28.2
28.0
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Chlorine exists as two isotopes with mass numbers 35 and 37. A sample of chlorine contains 75.3% of chlorine-35 atoms.
What is the relative atomic mass of chlorine in this sample, to 2dp?
35.16
36.00
35.49
35.00
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A sample of neon contains the following isotopes
Isotope | Percentage abundance |
20Ne | 90.92 |
21Ne | 0.26 |
22Ne | 8.82 |
What is the relative atomic mass of neon in this sample, to 2dp?
21.00
20.18
20.09
20.00
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Nitrogen trichloride has the formula NCl3, a sample was found to contain only nitrogen atoms with mass number 14, and chlorine atoms with mass numbers 35 and 37.
Which of the following ions and mass/charge ratio for the ions responsible for the molecular ion peaks in the mass spectrum of nitrogen trichloride is incorrect?
| Ion | m/e |
A | N(35Cl)3+ | 119 |
B | N(35Cl)237Cl+ | 121 |
C | N35Cl(37Cl)2+ | 123 |
D | N(37Cl)2+ | 125 |
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The mass spectrum of silicon is shown below.
What is the best estimate for the relative atomic mass of silicon in this sample?
29.0
28.8
28.3
28.0
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Which alcohol is not likely to have a fragment ion at m/e at 43 in its mass spectrum?
(CH3)2CHCH2OH
CH3CH(OH)CH2CH2CH3
CH3CH2CH2CH2OH
CH3CH2CH(OH)CH3
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Which of the compounds below is not likely to have a fragment ion at m/e = 43 in its mass spectrum?
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Assuming that chlorine has only two isotopes and hydrogen and carbon as one, how many molecular ion peaks will be shown in the mass spectrum of C4H6Cl4?
5
4
3
2
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Bromine exists as two isotopes 79Br and 81Br, which are found in almost equal abundance.
Which of the following statements is correct?
79Br is more reactive than 81Br.
The mass spectrum of C3H7Br has two molecular ion peaks at 122 and 124.
The atomic radius of 79Br is less than the atomic radius of 81Br.
The first ionisation energy of 79Br is less than the first ionisation energy of 81Br.
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Which alcohol is likely to have a fragment ion at m/e = 31 in its mass spectrum?
(CH3)2CHCH2OH
CH3CH(OH)CH2CH2CH3
CH3CH2CH2C(OH)(CH3)2
CH3CH2CH(OH)CH3
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Which pair of compounds would you expect to both have a singly charged peak at m/e = 29 in the mass spectrum?
Propan-1-ol and propanal
Propanal and propanone
Propan-2-ol and propanal
Propan-1-ol and propan-2-ol
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Which of the ketones listed would not be expected to have a peak in its mass spectrum at m/e = 57?
Hexan-3-one, CH3CH2CH2COCH2CH3
Pentan-3-one, CH3CH2COCH2CH3
3-methylbutanone, (CH3)2CHCOCH3
Butanone, CH3CH2COCH3
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Chlorine has two isotopes, 35Cl and 37Cl.
What is the number of molecular ion peaks in the mass spectrum of a sample of Cl2?
5
4
3
2
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Which of the following statements about the mass spectrum of CH3Br is correct?
There is one peak for the molecular ion with an m/e value of 44.
There is one peak for the molecular ion with an m/e value of 95.
The last two peaks have abundances in the ratio 3:1 and occur at m/e values of 94 and 96.
The last two peaks are of equal size and occur at m/e values of 94 and 96.
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Two stable isotopes of bromine have relative masses of 79 and 81.
Which is the correct pattern of peaks in the mass spectrum of molecular bromine?
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The mass spectra of three compounds A, B and C are shown below.
Which of the following features of the three compounds A, B and C shows the molecular formula is C4H10O?
All show a molecular ion peak at 74
All show a molecular ion peak at 13
All show a molecular ion peak at 73
All show a molecular ion peak at 33
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Chlorine exists as two isotopes 35Cl and 37Cl in the ratio 3:1.
Which of the following statements about the molecular ion peaks in the mass spectrum of Cl2 is correct?
Peaks at m/e = 70 and 72 in the ratio 3:1
Peaks at m/e = 70, 72 and 74 in the ratio 9:3:1
Peaks at m/e = 70, 72 and 74 in the ratio 9:6:1
Peaks at m/e = 70 and 74 in the ratio 3:1
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A compound XFn is a fluoride of another halogen, X, and it is known that n > 1. The highest mass peak in the spectrum of XFn is assigned to the parent ion and comes as single peak at m/e = 222.
Which of the following statements is incorrect?
n = 5
The compound could contain bromine
X and F are monotopic
The compound is a fluoride of iodine
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In the mass spectrum of trifluoroacetic acid, CF3CO2H, intense peaks are observed at m/e = 69 and 45 (base peak) in addition to other peaks.
The peak at m/e = 69 is accompanied by a peak at m/e = 70, which is about 1.1% the intensity of the peak at m/e = 69.
Which of the following statements is not supported by this information?
C−C bond cleavage occurs
Fluorine is monotopic
[HO2C]+ is a fragment ion
CF3CO2H fragments by sequential loss of F atoms
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A sample is analysed by mass spectrometry and infrared spectroscopy. The following incomplete data is obtained.
Mass spectrometry | Infrared spectroscopy |
Molecular ion peak at m/e = 128 | Sharp peak at 1720 cm-1 |
Fragment ion peak at m/e = 15 | No broad peak around 3200 cm-1 |
Which of the following compounds is demonstrated by this data?
Bond | Wavenumber range / cm-1 |
C−O; hydroxyl, ester | 1040 – 1300 |
C═C; aromatic compound, alkene | 1500 - 1680 |
C═O amide carbonyl, carboxyl ester | 1640 – 1690 1670 – 1740 1710 - 1750 |
C≡N; nitrile | 2200 – 2250 |
C−H; alkane | 2850 – 2950 |
N−H; amine, amide | 3300 – 3500 |
O−H; carboxyl hydroxyl | 2500 – 3000 3200 - 3600 |
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