A Level Chemistry OCR Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

A carbanion is indeed defined as an organic ion where a carbon atom carries a negative charge. This negatively charged species forms when a carbon atom has more electrons than usual, typically resulting from the addition of an electron or the removal of a proton from a carbon-hydrogen bond. Carbanions play an essential role in various organic reactions, particularly in nucleophilic reactions, where the negatively charged carbon atom acts as a strong nucleophile.

The structure and stability of carbanions can vary significantly depending on their environment, such as the presence of electron-withdrawing or electron-donating groups. In contrast, an organic ion carrying a positive charge represents a different type of ion known as a carbocation, not a carbanion. A neutral organic molecule does not carry any charge, while ions derived from oxygen would refer to oxyanions—not carbanions.

Therefore, B accurately captures the essence of what a carbanion is.