Q143 / 200 · MHT CET - Medical 2026 (22 April Shift 1) · Chemistry
An organic compound 'A' ($\text{C}_3\text{H}_6\text{O}$) gives a positive iodoform test but does not reduce Tollens' reagent. Identify the compound 'A':
- A$\text{CH}_3\text{CH}_2\text{CHO}$
- B$\text{CH}_3\text{CHOHCH}_3$
- Correct answerC$\text{CH}_3\text{COCH}_3$
- D$\text{CH}_3\text{CH}_2\text{CH}_2\text{OH}$
Solution
The given organic compound 'A' has the molecular formula $\text{C}_3\text{H}_6\text{O}$.
Since it does not reduce Tollens' reagent, it is not an aldehyde. Therefore, it must be a ketone.
Since it gives a positive iodoform test, it must contain a methyl ketone group ($\text{CH}_3\text{CO}-$).
The only ketone with the molecular formula $\text{C}_3\text{H}_6\text{O}$ is propanone (acetone), which is $\text{CH}_3\text{COCH}_3$.
Note that while propan-2-ol ($\text{CH}_3\text{CHOHCH}_3$) also gives a positive iodoform test and does not reduce Tollens' reagent, its molecular formula is $\text{C}_3\text{H}_8\text{O}$, which does not match the given formula.
Answer: $\text{CH}_3\text{COCH}_3$
Since it does not reduce Tollens' reagent, it is not an aldehyde. Therefore, it must be a ketone.
Since it gives a positive iodoform test, it must contain a methyl ketone group ($\text{CH}_3\text{CO}-$).
The only ketone with the molecular formula $\text{C}_3\text{H}_6\text{O}$ is propanone (acetone), which is $\text{CH}_3\text{COCH}_3$.
Note that while propan-2-ol ($\text{CH}_3\text{CHOHCH}_3$) also gives a positive iodoform test and does not reduce Tollens' reagent, its molecular formula is $\text{C}_3\text{H}_8\text{O}$, which does not match the given formula.
Answer: $\text{CH}_3\text{COCH}_3$
Hence, the correct answer is option: 'C'.