Final answer:
Information about functional groups can be obtained by examining the IR spectrum, which is useful for identifying functional groups' characteristic absorption frequencies.
Step-by-step explanation:
The student's question pertains to the identification of functional groups in organic molecules using various spectroscopic techniques. Among the given options, the IR spectrum is the most informative for identifying functional groups because different groups exhibit characteristic absorption frequencies that can be detected by infrared spectroscopy. For instance, the carbonyl group of a ketone typically has an absorbance in the range of 1710-1750 cm-1, while alkynes show absorbance peaks around 2100-2250 cm-1 due to the stretching of the carbon-carbon triple bond.
This valuable tool can be used in conjunction with other methods to deduce the presence or absence of functional groups in a molecule. For example, checking if the ketone group of cyclohexanone has been converted to an alcohol group in cyclohexanol can be determined by comparing the IR spectra of the starting compound and reaction product. Furthermore, IR spectroscopy can assist in verifying the chemical reactivity patterns that are characteristic of various functional groups, helping to predict the behaviors of organic compounds.
When observing the IR spectra of unknown samples, the presence of absorbance at certain frequencies can infer the presence of specific functional groups, which is fundamental in structural elucidation of organic compounds.