Which of the following compounds is least reactive towards nucleophilic addition?

Step-by-step solution

The reactivity of carbonyl compounds towards nucleophilic addition depends on steric and electronic factors. Reactivity decreases as the size and number of alkyl groups attached to the carbonyl carbon increase, due to greater steric hindrance and increased +I (electron-donating) effect, which reduces the electrophilicity of the carbonyl carbon. Methanal ( HCHO ) has no alkyl groups and is the most reactive. Propanone ( CH₃COCH₃ ) has two small methyl groups. 2-Pentanone ( CH₃COCH₂CH₂CH₃ ) has one methyl and one pro