See image — Alcohols Phenols and Ethers Chemistry Question

💡 Solution & Explanation

The iodoform test is positive for compounds that have the structural feature of a methyl ketone (CH3CO-), ethanol (CH3CH2OH), acetaldehyde (CH3CHO), or secondary alcohols of the type CH3CH(OH)R, as well as any compound that can be oxidized to these under the reaction conditions. Conditions for a positive iodoform test: 1. Methyl ketones (CH3COR) 2. Acetaldehyde (CH3CHO, ethanal) 3. Ethanol (CH3CH2OH) — oxidized to acetaldehyde by I2/NaOH 4. Secondary alcohols with the CH3CH(OH)- group (e.g., isopropyl alcohol, propanol-2) 5. Acetone (propanone, CH3COCH3) Now evaluate each option: Option (a): methanol, ethanol, propanone - Methanol (CH3OH) does NOT give iodoform test (no CH3CO- or CH3CHOH- group). - Ethanol: YES. Propanone: YES. - Fails because methanol is negative. Option (b): ethanol, isopropanal, methanal - Isopropanal = propanal? or isopropyl aldehyde? Isopropanal is (CH3)2CHCHO — it lacks the CH3CO- group and is not ethanal, so it does NOT give iodoform test. - Methanal (HCHO, formaldehyde) does NOT give iodoform test. - Fails because isopropanal and methanal are negative. Option (c): ethanol, ethanal, isopropyl alcohol - Ethanol (CH3CH2OH): YES — oxidized to ethanal under iodoform conditions. - Ethanal (CH3CHO): YES — directly has CH3CHO structure. - Isopropyl alcohol (CH3CH(OH)CH3, propanol-2): YES — has CH3CH(OH)- group, oxidized to propanone (methyl ketone). - All three give positive iodoform test. Option (d): propanal, propanol-2, propanone - Propanal (CH3CH2CHO): does NOT give iodoform test (no CH3CO- group; the carbonyl carbon does not have a methyl group on it in the alpha position in the right way — propanal is CH3CH2CHO, not a methyl ketone or acetaldehyde). - Propanol-2: YES. Propanone: YES. - Fails because propanal is negative. Therefore, the correct answer is C.