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Which of the following reactions is used to **distinguish** acetophenone (PhCOCH₃) from benzaldehyde (PhCHO)?
ANeither gives any test
BBoth give positive iodoform test
CAcetophenone gives positive iodoform test (CH₃-CO- present); benzaldehyde does NOT (no CH₃-CO-). Conversely, benzaldehyde gives positive Tollens' (silver mirror); acetophenone does NOT
DBoth decolourise Br₂ in CCl₄
Answer & Solution
Correct answer: C. Acetophenone gives positive iodoform test (CH₃-CO- present); benzaldehyde does NOT (no CH₃-CO-). Conversely, benzaldehyde gives positive Tollens' (silver mirror); acetophenone does NOT
**Acetophenone (PhCOCH₃)**: methyl ketone → **positive iodoform (CHI₃ yellow ppt)**; ketone → **negative Tollens'**. **Benzaldehyde (PhCHO)**: not a methyl ketone → **negative iodoform**; is an aldehyde → **positive Tollens' (silver mirror)**. Used together, these two tests cleanly distinguish them. **Fehling's is negative for both** (aromatic).
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