The correct answer is B. Oxygen.
A carbonyl group is a functional group that consists of a carbon atom double-bonded to an oxygen atom. The carbon atom is also bonded to two other atoms or groups of atoms. The carbonyl group is found in many organic compounds, including aldehydes, ketones, and carboxylic acids.
The carbonyl group is a very reactive group. The carbon-oxygen double bond is polarized, with the oxygen atom having a partial negative charge and the carbon atom having a partial positive charge. This makes the carbon atom in the carbonyl group electrophilic, meaning that it is attracted to nucleophiles. The oxygen atom in the carbonyl group is also nucleophilic, meaning that it is attracted to electrophiles.
The carbonyl group is an important functional group in organic chemistry. It is found in many different types of compounds, and it plays a role in many different chemical reactions.
Here are brief explanations of each option:
- A. Carbon. A carbon atom can make a double bond with another carbon atom, but this is not a carbonyl group. A carbonyl group is a double bond between a carbon atom and an oxygen atom.
- B. Oxygen. A carbonyl group is a double bond between a carbon atom and an oxygen atom.
- C. Hydrogen. A carbonyl group does not have a hydrogen atom.
- D. None of the above. The correct answer is B. Oxygen.