•  The degree of unsaturation or index of hydrogen deficiency (IHD) can be used to determine from a molecular formula the number of rings or multiple bonds in a molecule.

•  Mass spectrometry (MS), proton nuclear magnetic resonance spectroscopy (1H NMR) and infrared spectroscopy (IR) are techniques that can be used to help identify compounds and to determine their structure.

•  Determination of the IHD from a molecular formula.

•  Deduction of information about the structural features of a compound from percentage  composition data, MS, 1H NMR or IR.

• The electromagnetic spectrum (EMS) is given in the data booklet in section 3. The regions         employed for each technique should be understood.

• The operating principles are not required for any of these methods.

• The data booklet contains characteristic ranges for IR absorptions (section 26), 1H NMR data (section 27) and specific MS fragments (section 28). For 1H NMR, only the ability to deduce the    number of different hydrogen (proton) environments and the relative numbers of hydrogen atoms in each environment is required. Integration traces should be covered but splitting patterns are not required.