A LEVEL CHEMISTRY
SPECTROSCOPY
MULTIPLE CHOICE QUESTIONS
1. The correct order for the basic features of a mass spectrometer is...
acceleration, deflection, detection, ionisation ionisation, acceleration, deflection, detection acceleration, ionisation, deflection, detection acceleration, deflection, ionisation, detection
2. Which one of the following statements about ionisation in a mass spectrometer is incorrect?
gaseous atoms are ionised by bombarding them with high energy electrons atoms are ionised so they can be accelerated atoms are ionised so they can be deflected it doesn't matter how much energy you use to ionise the atoms
3. The path of ions after deflection depends on...
only the mass of the ion only the charge on the ion both the charge and the mass of the ion neither the charge nor the mass of the ion
4. Which of the following species will be deflected to the greatest extent?
37Na+ 35Na+ 37Na 35Na2+
5. Which of the following is not a use for mass spectrometry?
calculating the isotopic abundance in elements investigating the elemental composition of planets confirming the presence of O-H and C=O in organic compounds calculating the molecular mass of organic compounds
6. Which one of the following statements about the mass spectrum of CH3Br is correct?
the last two peaks are of equal size and occur at m/z values of 94 and 96 the last two peaks have abundances in the ratio 3:1 and occur at m/z values of 94 and 96 there is just one peak for the molecular ion with an m/z value of 95 there is just one peak for the molecular ion with an m/z value of 44
7. Which one of the following pieces of information cannot be obtained from an infra-red spectrum?
the molecular mass the presence of C=O bonds the presence of O-H bonds the identity of a compound through comparison with other spectra
8. To check that a secondary alcohol has been completely oxidised to a ketone you can...
check that the IR spectrum has absorptions at 3500cm-1 and 1650cm-1 check that the IR spectrum has no absorption around 3500cm-1 check that the IR spectrum has no absorption around 1650cm-1 check that the IR spectrum no absorptions at 3500cm-1 and 1650cm-1
9. The region of an infra-red spectrum where many absorptions take place is known as the...
thumbprint region handprint region footprint region fingerprint region
10. Proton nmr is useful for investigating the structure of organic compounds because...
organic compounds contain carbon atoms organic compounds are mostly covalent hydrogen atoms are found in nearly all organic compounds organic compounds have low boiling points
11. Which of the following statements about tetramethylsilane is incorrect?
it produces a single peak at d=10 it is inert it is volatile and can be easily distilled off and used again it is used to provide a reference against which other peaks are measured
12. Signals in a proton nmr spectrum do not provide information about...
the relative number of hydrogen atoms in a particular environment the number of chemically different hydrogen atoms on adjacent atoms the environment of different hydrogen atoms in a molecule the molecular mass of an organic molecule
13. The proton nmr spectrum of propane will consist of...
a triplet and a singlet a triplet and a quartet a doublet and a sextet a triplet and a septet
14. The proton nmr of 1-bromopropane will consist of...
two doublets and a sextet a doublet and a septet a singlet, a doublet and a triplet two triplets and a sextet
15. The proton nmr of 2-bromopropane will consist of...
two doublets and a sextet a doublet and a septet a singlet, a doublet and a triplet a singlet, a doublet and a triplet
16. The proton nmr of 2-bromo-2-methylpropane will consist of...
three quartets and a singlet two doublets and a singlet two singlets one singlet
17. The splitting pattern for a signal is found by...
counting the number of chemically equivalent hydrogen atoms on adjacent atoms counting the number of chemically different hydrogen atoms on adjacent atoms counting the number of chemically different hydrogen atoms on adjacent atoms and adding 1 counting the number of chemically different hydrogen atoms on adjacent atoms and subtracting 1
18. Which one of the following statements about protons on O-H groups is incorrect?
they always produce a doublet they always produce a singlet they are not taken into account when working out splitting patterns of adjacent protons their signal can be removed from its normal location by shaking with deuterium oxide
19. The molecule HOCH2CH2OH will have an nmr spectrum consisting of...
two singlets a triplet and a doublet two doublets a singlet and a doublet
20. In a triplet, the relative peak areas are in the ratio...
1:1:1 1:2:1 1:3:1 1:4:1
21. Which compound has a molecular ion at m/z = 58, an infra red absorption at 1650cm-1
and just one singlet in its nmr spectrum?
butane CH3COCH3 CH3CH2CHO 2-methylpropane
22. Which one of the following hydrocarbons produces an nmr spectrum with more than one peak?
methane ethane butane cyclobutane
23. The isomer of C4H8 which produces an nmr spectrum with four different signals is...
CH2=CHCH2CH3 CH3CH=CHCH3 (CH3)2C=CH2 cyclobutane
24. To work out the molecular mass of an organic molecule you would look at its...
infra red spectrum mass spectrum proton nmr spectrum boiling point
25. Which one of the following methods would be best for finding the identity of an organic compound?
finding the m/z value of the molecular ion in its mass spectrum its proton nmr spectrum comparing its infra red spectrum with known examples measuring its melting point