Iodoform reaction produces CHI₃ precipitate and specific carboxylate ions

Steps:

• Alkaline I₂(aq) performs iodoform test on methyl ketones (CH₃COR), forming yellow CHI₃ precipitate and RCO₂⁻ ions.
• Yellow precipitate identifies CHI₃; CH₃CO₂⁻ requires R = CH₃, so W = CH₃COCH₃ (propanone).
• Butanone (CH₃COCH₂CH₃) has R = CH₂CH₃, yielding CH₃CH₂CO₂⁻ instead.
• Options list CH₃I (not yellow precipitate) for all, mismatching CHI₃.

Why A is wrong:

• Butanone forms propanoate (CH₃CH₂CO₂⁻), not acetate; CH₃I is incorrect precipitate.

Why the others are wrong:

• B: No information provided.
• C: Propanone correct for CH₃CO₂⁻ but CH₃I wrong precipitate.
• D: Identical to C, incorrect precipitate.

Not enough information.

Final answer: Not enough information.