Final answer:
The bond angles around a carbonyl group's carbon atom are approximately 120° due to its trigonal planar geometry and sp² hybridization.
Step-by-step explanation:
The approximate bond angles about the carbon atom of a carbonyl group are 120°. In a carbonyl group, the carbon atom is sp² hybridized, which leads to a trigonal planar geometry with bond angles of about 120°. This geometry is due to the three regions of electron density (two single bonds and one double bond) around the carbon atom, which spread out to minimize repulsion, resulting in these bond angles.