Nucleophilic Addition to Aldehydes with HCN

Steps:

• Recognize CH3CHO as acetaldehyde, an aldehyde with a polar C=O bond where carbon is electrophilic.
• In the presence of CN-, cyanide ion acts as a nucleophile attacking the carbonyl carbon.
• H+ from HCN then protonates the oxygen, forming CH3CH(OH)CN.
• Name the product: carbon chain is three carbons (CH3-CH(OH)-CN), so 2-hydroxypropanenitrile.

Why C is correct:

• Aldehydes undergo nucleophilic addition with HCN; CN- adds to C=O (electrophile), yielding 2-hydroxypropanenitrile (CH3CH(OH)CN) per IUPAC naming for the three-carbon chain.

Why the others are wrong:

• A: Incorrect reaction type; carbonyls attract nucleophiles, not undergo electrophilic addition.
• B: Incorrect reaction type and product name; it's nucleophilic, and ethanenitrile implies two carbons (wrong for CH3CH(OH)CN).
• D: Incorrect product name; ethanenitrile (two carbons) mismatches the three-carbon structure from acetaldehyde.

Final answer: C