Evaluation of reaction mechanism statements Steps:

• Identify the reaction: propanone (ketone) + HCN forms cyanohydrin via nucleophilic addition.
• Analyze species roles: CN⁻ acts as nucleophile attacking electrophilic carbonyl carbon.
• Classify reaction type: addition across C=O π bond, forming tetrahedral intermediate.
• Examine bond changes: H-CN bond breaks heterolytically to generate CN⁻ and H⁺.

Why C is correct:

• Heterolytic bond breaking involves unequal electron distribution, as in H-CN → H⁺ + CN⁻, where the electron pair stays with CN per the definition of heterolysis.

Why the others are wrong:

• A: CN⁻ is a nucleophile (electron donor), not an electrophile (electron acceptor).
• B: The reaction is an addition, but the mechanism shown may depict a different classification; not enough information.
• D: Not enough information (statement incomplete).

Final answer: C