On the Wiley homework there is a section about whether or not to expect an IR signal above or below 3000 cm^-1. For a few of the alkenes and alkynes it says that we should not expect a signal above 3000, but today in class we were told to expect C-H stretching above 3000 cm^-1. Can you clarify that? (This stretching is characteristic for H connected to an sp2- or sp-hybridized carbon, which is a part of a C=C bond or carbon-carbon triple bond. Therefore, this vibration will be observed for alkenes and alkynes with at least one H at a multiple bond, and will not observed for the rest of them. - GS).