What are the principle peaks in an IR spectra for benzoic acid?

Answer 1

Carbonyl around 1700

Carboxylic acid OH 2400-3000

C=C aromatic at 1600 & 1475

Answer 2

In the IR spectrum of benzoic acid, the principal peaks include a strong, broad peak in the range of 2500-3300 cm^-1 due to the O-H stretching vibration, a sharp peak around 1700 cm^-1 corresponding to the C=O stretching vibration, and peaks around 1300-1600 cm^-1 for C-C stretching vibrations of the aromatic ring.