Major Chemistry B.Sc.III ( Semester V)
Name of paper- Spectral analysis
CHE/DSC/T/301
Mass Spectroscopy
Multiple Choice
questions:
1. What does a mass spectrometer primarily measure?
A) Wavelength
of light
B) Mass-to-charge ratio (m/z)
C) Absorbance
D) Refractive index
Answer: B
2. The molecular ion is also known as the:
A) Base ion
B) Daughter ion
C) Parent ion
D) Radical ion
Answer: C
3. The peak having 100% relative intensity in a mass
spectrum is called the:
A) Molecular
ion peak
B) Isotopic peak
C) Base peak
D) Fragment peak
Answer: C
4. In a mass spectrum, the molecular ion peak generally
provides:
A) Functional
group
B) Molecular mass
C) Color of compound
D) Boiling point
Answer: B
5. Which fragmentation reaction involves β-bond cleavage
followed by γ-hydrogen transfer?
A) α-Cleavage
B) Retro-Diels–Alder reaction
C) McLafferty rearrangement
D) Heterolytic cleavage
Answer: C
6. According to the nitrogen rule, a compound with one
nitrogen atom will have:
A) Even
molecular mass
B) Odd molecular mass
C) Zero molecular mass
D) Any molecular mass
Answer: B
7. Which compounds typically show an M and M+2 peak in a
3:1 intensity ratio?
A) Bromo
compounds
B) Chloro compounds
C) Iodo compounds
D) Fluoro compounds
Answer: B
8. Which compounds show M and M+2 peaks of nearly equal
intensity?
A) Chloro
compounds
B) Fluoro compounds
C) Bromo compounds
D) Iodo compounds
Answer: C
9. The Rule of 13 is mainly used to determine:
A) Melting
point
B) Molecular formula
C) Optical activity
D) Solubility
Answer: B
10. The base formula in the Rule of 13 is obtained by
dividing the molecular mass by:
A) 10
B) 12
C) 13
D) 14
Answer: C
11. Which ion is characteristic of a primary alcohol?
A) m/z 45
B) m/z 59
C) m/z 31
D) m/z 77
Answer: C
12. A peak at m/z 91 is characteristic of:
A) Benzene ring
B) Tropylium ion
C) Carbonyl ion
D) Oxonium ion
Answer: B
13. The molecular ion peak of benzene appears at:
A) m/z 44
B) m/z 57
C) m/z 78
D) m/z 91
Answer: C
14. Which ion is typically the base peak in
2,2,4-trimethylpentane (isooctane)?
A) m/z 114
B) m/z 99
C) m/z 57
D) m/z 78
Answer: C
15. Which type of alcohol usually does not show a
detectable molecular ion peak?
A) Primary
alcohol
B) Secondary alcohol
C) Tertiary alcohol
D) Allyl alcohol
Answer: C
16. A prominent peak at m/z 77 generally indicates the
presence of:
A) Fluorine
B) Benzene ring
C) Bromine
D) Sulfur
Answer: B
17. The fragmentation most common in aldehydes and
ketones is:
A) α-Cleavage
B) β-Cleavage only
C) Retro-Diels–Alder reaction only
D) Ortho-elimination only
Answer: A
18. The parent ion abundance generally decreases with
increasing:
A) Aromaticity
B) Conjugation
C) Molecular weight in a homologous series
D) Number of double bonds
Answer: C
19. Which halogen compound generally gives the strongest
molecular ion peak among aliphatic halides?
A) Alkyl
fluoride
B) Alkyl chloride
C) Alkyl bromide
D) Alkyl iodide
Answer: D
20. Which analytical technique is considered one of the
most accurate methods for determining molecular mass?
A) UV
Spectroscopy
B) IR Spectroscopy
C) Mass Spectrometry
D) Flame Test
Answer: C
21. Which of the following compounds gives a strong
molecular ion peak due to the presence of a π-electron system?
A) Alcohols
B) Aromatic compounds
C) Branched alkanes
D) Ethers
Answer: B
22. A peak at m/z 19 in a mass spectrum indicates the
presence of:
A) Chlorine
B) Fluorine
C) Bromine
D) Sulfur
Answer: B
23. A peak at m/z 30 is characteristic of:
A) Primary
amines
B) Alcohols
C) Ketones
D) Aromatic compounds
Answer: A
24. In straight-chain aldehydes containing a γ-hydrogen
atom, the McLafferty rearrangement produces a prominent peak at:
A) m/z 31
B) m/z 43
C) m/z 44
D) m/z 58
Answer: C
25. Which of the following factors decreases the
intensity of the molecular ion peak?
A) Aromaticity
B) Conjugation
C) Branching
D) Unsaturation
Answer: C
26. The ion CH₂=OH⁺ observed at m/z 31 is called:
A) Acylium ion
B) Oxonium ion
C) Allyl ion
D) Benzyl ion
Answer: B
27. Which fragmentation is characteristic of cyclic
olefins?
A) α-Cleavage
B) McLafferty rearrangement
C) Retro-Diels–Alder reaction
D) β-Cleavage
Answer: C
28. In aliphatic ketones, α-cleavage generally gives
peaks at:
A) m/z 18, 28
B) m/z 43, 57, 71
C) m/z 77, 91
D) m/z 31, 45
Answer: B
29. Straight-chain chlorides with more than six carbon
atoms commonly give the most intense ion at:
A) C₂H₅Cl⁺
B) C₃H₆Cl⁺
C) C₄H₈Cl⁺
D) C₅H₁₀Cl⁺
Answer: C
30. In the mass spectrum of ethyl chloride, the molecular
ion peaks appear at:
A) m/z 29 and
31
B) m/z 64 and 66
C) m/z 78 and 80
D) m/z 98 and 100
Answer: B
Mass Spectroscopy Part-I
Mass Spectroscopy Part-II
Mass Spectroscopy Problems
Mass Spectroscopy Multiple choice questions
Proton magnetic resonance spectroscopy
