Tests for functional groups yielding colored products Steps:

• Identify the reagent and its purpose: 2,4-DNPH tests for carbonyls (orange ppt); dichromate oxidizes alcohols (color change in reagent); KMnO4 tests for unsaturation (decolorizes reagent).
• Analyze each reaction with ethanol: A forms no product (no carbonyl); B oxidizes to acetaldehyde/acetic acid (both colorless); C shows no reaction (no unsaturation).
• Recall that colored organic products arise from specific tests like DNPH with carbonyls, not alcohol oxidations.
• Conclude D involves a reaction (e.g., carbonyl + DNPH) producing a visible color, unlike A–C.

Why D is correct:

• D features a carbonyl compound reacting with 2,4-DNPH to form an orange hydrazone precipitate, a standard colored organic product.

Why the others are wrong:

• A: Ethanol lacks a carbonyl, so no orange product forms.
• B: Oxidation yields colorless acetaldehyde or acetic acid; color change is in the inorganic reagent.
• C: No unsaturation in ethanol, so no reaction or colored product; reagent decolorizes only with alkenes.

Final answer: D