Final answer:
IR spectroscopy is used to identify functional groups in organic compounds based on their characteristic absorption frequencies. Nitriles show absorption peaks in the range of 2200-2300 cm-1, while alcohols exhibit a broad peak around 3300 cm-1. Alkenes/benzenes show strong absorption in the fingerprint region, and CH groups contribute to the IR spectrum. Option a is correct.
Step-by-step explanation:
Infrared (IR) spectroscopy is a technique used to identify functional groups in organic compounds by analysing their characteristic absorption frequencies. Nitriles, which contain the CN functional group, show a strong absorption peak in the range of 2200-2300 cm-1. Alcohols, with the OH functional group, exhibit a broad absorption peak around 3300 cm-1.
Alkenes/benzenes do not have specific absorption peaks in the IR region; however, they typically show strong absorption in the fingerprint region (400-1400 cm-1). CH groups, such as those present in hydrocarbons, do not have specific absorption peaks but contribute to the overall spectrum.