The functional groups in an organic compound can frequently be deduced from its infrared absorption spectrum. a hydrocarbon exhibits no bands above 3000 but gives weak absorption at 2200 cm-1. relative absorption intensity: (s)=strong, (m)=medium, (w)=weak. what functional class(es) does the compound belong to? list only classes for which evidence is given here. attach no significance to evidence not cited explicitly. do not over-interpret exact absorption band positions. none of your inferences should depend on small differences like 10 to 20 cm-1.