See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Concept: In a carbonyl group (C=O), the carbon and oxygen atoms have different electronic characters. Oxygen is more electronegative than carbon, so the pi electrons of the C=O bond are pulled toward oxygen. This creates a partial positive charge (δ+) on the carbonyl carbon and a partial negative charge (δ−) on the oxygen. Reasoning: A nucleophile is an electron-rich species that seeks electron-deficient (electrophilic) sites. Because the carbonyl carbon bears a δ+ charge due to the electron-withdrawing effect of oxygen, it is the electrophilic center in a ketone. The nucleophile therefore directs its attack at the carbonyl carbon, forming a tetrahedral intermediate (an alkoxide). This is the classic nucleophilic addition mechanism for ketones and aldehydes. Why other options fail: - (b) The oxygen atom is electron-rich (δ−), so it is not attacked by a nucleophile; it can act as an electrophilic site only for very hard Lewis acids or protons. - (c) Attack does not occur with equal probability at both atoms; the carbonyl carbon is overwhelmingly the site of nucleophilic attack. - (d) Ketones do react with nucleophiles via nucleophilic addition; they are simply less reactive than aldehydes due to steric and electronic factors, but they are not unreactive. Therefore, the correct answer is A.