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