Practice question

In infrared spectroscopy, region from 4000 to 1000 cm-1, especially 4000-1500 cm-1, is designated functional group region because fundamental stretches of diagnostic bonds absorb with minimal coupling. Strong absorptions for X-H stretches including O-H, N-H, C-H near 3700-2800, triple bonds near 2260-2100, double bonds C=O, C=C near 1850-1550 cm-1 appear here, enabling quick classification of alcohols, amines, alkynes and carbonyls in biomolecules. Below 1000 cm-1 vibrations overlap producing fingerprint pattern reflecting molecular skeleton, better suited for identity confirmation than functional assignment, distinguishing primary chemistry from overall fingerprint.