Which of the following statements correctly identifies the infrared regions for O-H and C=O groups?

• A. O-H around 3200-3600 cm^-1 and C=O around ~1700 cm^-1
• B. O-H around 1400 cm^-1
• C. O-H around 2600 cm^-1
• D. O-H around 3200-3600 cm^-1 and C=O around ~1900 cm^-1

Answer: (A)

Infrared spectroscopy reveals characteristic bond vibrations: the O-H stretch typically appears as a strong, broad band from about 3200 to 3600 cm^-1, while the carbonyl C=O stretch shows up around 1700 cm^-1 (often 1650–1750 cm^-1 depending on the molecule’s environment). Therefore, the statement assigning O-H in 3200–3600 cm^-1 and C=O near 1700 cm^-1 matches these well-known regions. The other options place the O-H at nonstandard positions (for example, 1400 cm^-1 is more associated with bending modes, not the main O-H stretch) or misplace the carbonyl frequency (1900 cm^-1 is higher than typical for C=O stretches in most carbonyl-containing groups).