A LevelChemistryCambridge (CIE)Exam Questions22. Analytical TechniquesMass Spectrometry

Mass Spectrometry (Cambridge (CIE) A Level Chemistry): Exam Questions

Exam code: 9701

1 hour30 questions

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Mass Spectrometry

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1
1 mark

Which of the following corresponds to the base peak in a mass spectrum?

  • Any fragment ion

  • The ion with the lowest m/z ratio

  • The molecular ion

  • The most abundant ion

Choose your answer

2
1 mark

The diagram shows the structural formula of ricinoleic acid.

Structural formula of ricinoleic acid (12-hydroxyoctadec-9-enoic acid), an 18-carbon chain with a carboxylic acid group at C-1, a cis C=C double bond between C-9 and C-10, and a hydroxyl group at C-12

The mass spectrum of ricinoleic acid shows a peak at m/z = 55.

Which fragment ion is responsible for this peak?

  • C4H7+

  • CH2CO2+

  • CH≡CHCHOH+

  • COOH+

Choose your answer

3
1 mark

In a mass spectrometer, the ions are separated.

Which of the following species will be deflected to the greatest extent?

  • 35Cl+

  • 35Cl2+

  • 37Cl

  • 37Cl+

Choose your answer

4
1 mark

A sample of silicon contains the following isotopes.

Isotope

Percentage abundance

28Si

81.21

29Si

14.10

30Si

4.69

Which is the relative atomic mass of silicon in this sample, to 1 dp?

  • 28.0

  • 28.2

  • 29.0

  • 29.8

Choose your answer

5
1 mark

Chlorine exists as two isotopes with mass numbers 35 and 37. A sample of chlorine contains 75.3% of chlorine-35 atoms.

Which is the relative atomic mass of chlorine in this sample, to 2 dp?

  • 35.00

  • 35.49

  • 36.00

  • 36.51

Choose your answer

6
1 mark

A sample of neon contains the following isotopes.

Isotope

Percentage abundance

20Ne

90.92

21Ne

0.26

22Ne

8.82

Which is the relative atomic mass of neon in this sample, to 2 dp?

  • 20.00

  • 20.09

  • 20.18

  • 21.00

Choose your answer

7
1 mark

Nitrogen trichloride has the formula NCl3. A sample contains only 14N atoms and chlorine atoms with mass numbers 35 and 37.

Which ion and m/z value in the table is not correct?

Ion

m/z

A

[14N(35Cl)3]+

119

B

[14N(35Cl)2(37Cl)]+

121

C

[14N(35Cl)(37Cl)2]+

123

D

[14N(37Cl)2]+

125

    Choose your answer

    8
    1 mark

    The mass spectrum of silicon is shown below.

    Mass spectrum of a silicon sample showing three peaks: the tallest at m/z = 28 (approximately 80% relative abundance), a medium peak at m/z = 29 (approximately 12%), and a small peak at m/z = 30 (approximately 8%)

    Which is the relative atomic mass of silicon in this sample, to 1 dp?

    • 28.0

    • 28.3

    • 28.8

    • 29.0

    Choose your answer

    1
    1 mark

    Which alcohol does not have a fragment ion at m/z = 43 in its mass spectrum?

    • (CH3)2CHCH2OH

    • CH3CH(OH)CH2CH2CH3

    • CH3CH2CH(OH)CH3

    • CH3CH2CH2CH2OH

    Choose your answer

    2
    1 mark

    Which of the compounds below is not likely to have a fragment ion at m/z = 43 in its mass spectrum?

    • Structural formula of propanoic acid (CH3CH2COOH, Mr = 74), which cannot produce a fragment at m/z = 43
    • [Structural formula of a compound containing a CH3CO unit, capable of producing a [CH3CO]+ fragment at m/z = 43]
    • [Structural formula of a compound containing an (CH3)2CH unit, capable of producing a [(CH3)2CH]+ fragment at m/z = 43]
    • [Structural formula of a compound containing a CH3CH2CH2 unit, capable of producing a [CH3CH2CH2]+ fragment at m/z = 43]

    Choose your answer

    3
    1 mark

    Assuming chlorine exists as two isotopes and that carbon and hydrogen each exist as a single stable isotope only, how many molecular ion peaks are shown in the mass spectrum of C4H6Cl4?

    • 2

    • 3

    • 4

    • 5

    Choose your answer

    4
    1 mark

    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.

    Choose your answer

    5
    1 mark

    Which alcohol is likely to have a fragment ion at m/z = 31 in its mass spectrum?

    • (CH3)2CHCH2OH

    • CH3CH(OH)CH2CH2CH3

    • CH3CH2CH2C(OH)(CH3)2

    • CH3CH2CH(OH)CH3

    Choose your answer

    6
    1 mark

    Which pair of compounds would you expect to both have a singly charged peak at m/z = 29 in the mass spectrum?

    • Propan-1-ol and propan-2-ol

    • Propan-1-ol and propanal

    • Propan-2-ol and propanal

    • Propanal and propanone

    Choose your answer

    7
    1 mark

    Which of the ketones listed would not be expected to have a peak in its mass spectrum at m/z = 57?

    • (CH3)2CHCOCH3

    • CH3CH2CH2COCH2CH3

    • CH3CH2COCH2CH3

    • CH3CH2COCH3

    Choose your answer

    8
    1 mark

    Chlorine has two isotopes, 35Cl and 37Cl.

    Which of the following is the number of molecular ion peaks in the mass spectrum of a sample of Cl2?

    • 2

    • 3

    • 4

    • 5

    Choose your answer

    9
    1 mark

    Which of the following statements about the mass spectrum of CH3Br is correct?

    • The molecular ion peaks are of equal size and occur at m/z values of 94 and 96.

    • The molecular ion peaks have abundances in the ratio 3:1 and occur at m/z values of 94 and 96.

    • There is one peak for the molecular ion with an m/z value of 44.

    • There is one peak for the molecular ion with an m/z value of 95.

    Choose your answer

    1
    1 mark

    Two stable isotopes of bromine, 79Br and 81Br, exist in approximately equal abundance.

    Which is the correct pattern of peaks in the mass spectrum of Br2?

    • Mass spectrum of Br2 showing a single molecular ion peak at m/z = 158, with no M+2 or M+4 peaks
    • Mass spectrum of Br2 showing a single molecular ion peak at m/z = 160, with Br+ fragment peaks at m/z = 79 and 81
    • Mass spectrum of Br2 showing five peaks: Br+ fragment ions at m/z = 79 and 81 of equal height, and molecular ion peaks at m/z = 158, 160 and 162 in a 1:2:1 ratio
    • Mass spectrum of Br2 showing three molecular ion peaks at m/z = 158, 160 and 162 in an incorrect 9:6:1 ratio, with Br+ fragment peaks at m/z = 79 and 81

    Choose your answer

    2
    1 mark

    The mass spectra of three compounds A, B and C are shown below.

    Mass spectrum of compound A, a C4H10O isomer, showing a molecular ion peak at m/z = 74 and fragment ion peaks at lower m/z values
    Mass spectrum of compound B, a C4H10O isomer, showing a molecular ion peak at m/z = 74 and fragment ion peaks at lower m/z values
    Mass spectrum of compound C, a C4H10O isomer, showing a molecular ion peak at m/z = 74 and fragment ion peaks at lower m/z values

    Which feature of the three mass spectra confirms that all three compounds have the molecular formula C4H10O?

    • All show a base peak at m/z = 73

    • All show a fragment ion peak at m/z = 15

    • All show a fragment ion peak at m/z = 33

    • All show a molecular ion peak at m/z = 74

    Choose your answer

    3
    1 mark

    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/z = 70 and 72 in the ratio 3:1

    • Peaks at m/z = 70 and 74 in the ratio 3:1

    • Peaks at m/z = 70, 72 and 74 in the ratio 9:3:1

    • Peaks at m/z = 70, 72 and 74 in the ratio 9:6:1

    Choose your answer

    4
    1 mark

    A compound XFn is a fluoride of another halogen, X, and it is known that n > 1. The highest mass peak in the mass spectrum of XFn is assigned to the molecular ion and appears as a single peak at m/z = 222.

    Which of the following statements is not correct?

    • n = 5

    • The compound could contain bromine

    • The compound is a fluoride of iodine

    • X and F each exist as a single stable isotope

    Choose your answer

    5
    1 mark

    In the mass spectrum of trifluoroacetic acid, CF3CO2H, intense peaks are observed at m/z = 69 and 45 (base peak) in addition to other peaks.

    The peak at m/z = 69 is accompanied by a peak at m/z = 70, which is about 1.1% the intensity of the peak at m/z = 69.

    Which of the following statements is not supported by this information?

    • C−C bond cleavage occurs

    • CF3CO2H fragments by sequential loss of F atoms

    • Fluorine exists as a single stable isotope

    • [HO2C]+ is a fragment ion

    Choose your answer

    6
    1 mark

    A sample is analysed by mass spectrometry and infrared spectroscopy. The data obtained are shown below.

    Mass spectrometry

    Infrared spectroscopy

    Molecular ion peak at m/z = 128

    Strong absorption at 1720 cm-1

    Fragment ion peak at m/z = 15

    No broad absorption around 3200 cm-1

    Which compound is consistent with these spectroscopic data?

    • Structural formula of compound A (Mr = 128), a carbonyl-containing compound with a terminal methyl group and no hydroxyl group
    • Structural formula of compound B, containing a hydroxyl OH group
    • Structural formula of compound C, with a relative molecular mass that does not equal 128
    • Structural formula of compound D, containing both a carbonyl C=O group and a hydroxyl OH group

    Choose your answer