See image — Practical Organic Chemistry and Purification Chemistry Question

💡 Solution & Explanation

Concept: To separate two carbonyl compounds, we need a reagent that reacts selectively with only one of them, forming an insoluble or easily separable product. Step 1: Identify the two compounds. Acetaldehyde (CH3CHO) is an aliphatic aldehyde. Acetophenone (C6H5COCH3) is an aryl ketone. Step 2: Evaluate Tollen's reagent (ammoniacal silver nitrate, [Ag(NH3)2]+OH-). Tollen's reagent is a mild oxidizing agent that selectively oxidizes aldehydes but does NOT oxidize ketones. Acetaldehyde (an aldehyde) reacts with Tollen's reagent to give a silver mirror (or silver precipitate) and acetic acid, while acetophenone (a ketone) does not react. Step 3: This selective reaction allows separation — acetaldehyde is consumed/converted while acetophenone remains unreacted, enabling their separation. Step 4: Why other options fail: - (a) NH2OH (hydroxylamine): Reacts with BOTH aldehydes and ketones to form oximes, so it cannot selectively separate them. - (b) NaOI (sodium hypoiodite/iodoform reagent): Both acetaldehyde and acetophenone give positive iodoform tests (both have CH3CO- group), so NaOI reacts with both and cannot separate them. - (d) C6H5NHNH2 (phenylhydrazine): Reacts with both aldehydes and ketones to form phenylhydrazones, so it cannot selectively separate them. Therefore, Tollen's reagent selectively reacts with acetaldehyde (aldehyde) and not with acetophenone (ketone), making it the correct reagent for separation. Therefore, the correct answer is C.