Answer:-

Aldehydes are generally more reactive toward nucleophilic addition reactions compared to ketones, and this can be explained by several factors:

1. Steric Hindrance: Aldehydes have a hydrogen atom bonded to the carbonyl carbon, whereas ketones have two alkyl or aryl groups bonded to the carbonyl carbon. The presence of a bulky alkyl or aryl group in ketones can create steric hindrance, making it more difficult for nucleophiles to approach the carbonyl carbon. In contrast, aldehydes have a smaller hydrogen atom, which allows nucleophiles to approach more easily.

2. Electron-Withdrawing Effect of Alkyl Groups: The alkyl groups attached to the carbonyl carbon in ketones have an electron-releasing (electron-donating) effect, which can reduce the electrophilicity of the carbonyl carbon. This electron-donating effect of alkyl groups in ketones makes them less attractive to nucleophiles compared to the carbonyl carbon in aldehydes, which has no alkyl group attached and is relatively more electrophilic.

3. Partial Positive Charge: In both aldehydes and ketones, the carbonyl carbon has a partial positive charge due to the electronegativity of oxygen. However, in aldehydes, this positive charge is more pronounced because there is only one alkyl group (or hydrogen) attached to the carbonyl carbon. This increased positive charge enhances the electrophilicity of the carbonyl carbon, making it more susceptible to nucleophilic attack.

4. Resonance Stabilization: In some cases, ketones can be stabilized by resonance structures, which can reduce their reactivity toward nucleophiles. For example, in β-diketones, resonance can delocalize the electron density in the carbonyl group, making it less electrophilic.

In summary, the combination of steric hindrance, the electron-withdrawing effect of alkyl groups, the partial positive charge on the carbonyl carbon, and resonance stabilization (in some cases) all contribute to the higher reactivity of aldehydes toward nucleophilic addition reactions compared to ketones.