Which of these techniques allows us to determine whether or not an organic molecule contains conjugation (a sequence of alternating single and double (or triple) bonds?Group of answer choicescombustion analysisUV/Vis spectroscopyIR spectroscopymass spectrometry1H NMR spectroscopy

The technique that allows us to determine whether or not an organic molecule contains conjugation (a sequence of alternating single and double or triple bonds) is UV/Vis Spectroscopy.

UV/Vis spectroscopy measures the absorption of light in the ultraviolet and visible ranges. Molecules with conjugated systems have pi electrons that can absorb energy from light in these ranges, causing electronic transitions. The specific wavelengths absorbed can provide information about the extent of conjugation in the molecule.

The other techniques listed (combustion analysis, IR spectroscopy, mass spectrometry, 1H NMR spectroscopy) provide different types of information:

• Combustion analysis provides information about the amount of carbon, hydrogen, and oxygen in a compound, which can be used to determine the empirical formula.
• IR spectroscopy provides information about the functional groups present in a molecule.
• Mass spectrometry provides information about the molecular weight of the compound and its structure.
• 1H NMR spectroscopy provides information about the number and type of hydrogen atoms in a molecule.