Iodoform and Tollens' Tests for Carbonyls

Steps:

• Identify structures: X is acetaldehyde (CH₃CHO), Y is acetone (CH₃COCH₃), Z is propanal (CH₃CH₂CHO).
• Recall iodoform test (alkaline iodine): Positive for methyl ketones (CH₃CO-) and acetaldehyde; X and Y react, Z does not.
• Recall Tollens' reagent: Oxidizes aldehydes to carboxylic acids; ketones like Y do not react.
• Evaluate statements: 1 true (X gives iodoform), 2 false (Y inert to Tollens'), 3 true (Z no iodoform).

Why A is correct:

• A identifies statements 1 and 3 as true, matching iodoform reactivity for acetaldehyde (X) and non-methyl carbonyl (Z).

Why the others are wrong:

• B includes statement 2, but ketones do not reduce Tollens' reagent.
• C excludes statement 1, but acetaldehyde gives iodoform via CH₃CH(OH)- formation.
• D excludes statement 3, but propanal lacks CH₃CO- for iodoform.

Final answer: A