Selecting the right spectroscopy for compound analysis

Steps:

• Infrared (IR) spectroscopy identifies functional groups by measuring molecular vibrations at specific wavelengths.
• Mass spectrometry (MS) determines molecular weight, fragmentation patterns, and ionization energies through ion detection.
• For organic compounds, functional group identification requires IR's absorption bands, not MS's mass-to-charge ratios.
• Successive ionization energies involve electron removal processes best tracked by MS, but IR provides no such data.

Why A is correct:

• IR spectroscopy detects characteristic absorption frequencies tied to functional group bonds, per Hooke's law for vibrational energy (E = hν).

Why the others are wrong:

• B: MS analyzes ion masses and fragments but cannot directly reveal functional group vibrations.
• C: IR measures bond vibrations, not electron ionization processes or energies.
• D: MS can measure Na's ionization energies, but the query specifies a compound, not an element like Na.

Final answer: A