Mass spectrometry for structure determination Quiz
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5 questions, one answer each
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1. What is the accurate relative molecular mass of C₂H₆O?
- A. 46.0054
- B. 46.0417
- C. 46.0000
- D. 45.9929
2. Why do N₂ and CO have different accurate relative molecular masses?
- A. They contain different numbers of electrons
- B. They are ionised differently
- C. The isotope masses are not whole numbers, so the totals differ
- D. N₂ contains ¹³C
3. A peak is measured at m/z 46.0054. Which formula fits?
- A. C₂H₆O
- B. NO₂
- C. C₃H₆O
- D. CH₂O₂
4. Why can two isomers not be distinguished by their accurate molecular ion peaks?
- A. Isomers do not form molecular ions
- B. Isomers have different nominal masses
- C. Isomers have the same molecular formula, so the same accurate Mᵣ
- D. High-resolution spectrometers cannot detect isomers
5. A low-resolution mass spectrum gives the molecular ion peak as m/z 58. Which statement is correct?
- A. The compound must be C₃H₆O
- B. The compound cannot be a hydrocarbon
- C. The formula is one of several with a nominal mass of 58
- D. The accurate mass is exactly 58.0000