Which of the following is most likely to react as a base rather than a nucleophile?

Question

Quizplus · Accepted Answer

Among the given options, IV is the most likely to react as a base because it has a lone pair of electrons on the nitrogen atom, which can accept a proton to form a positively charged nitrogen center. This makes IV a Brønsted-Lowry base. In contrast, options I, II, and III are likely to react as nucleophiles because they have a negative charge or a partial negative charge, which can be used to attack an electrophile.

Which of the Following Is Most Likely to React as a Base