Match Mixture of Organic Compounds with Reagents Used to Distinguish

To determine the correct matching between the mixtures of organic compounds in List - I and the distinguishing reagents in List - II, we analyze each pair individually based on their characteristic chemical tests:

1. A. Diethyl amine + Ethyl amine

   • Ethyl amine ($\text{CH}_3\text{CH}_2\text{NH}_2$) is a primary ($1^\circ$) amine, while diethyl amine ($(\text{CH}_3\text{CH}_2)_2\text{NH}$) is a secondary ($2^\circ$) amine.
   • Primary amines undergo the Carbylamine reaction when heated with chloroform and alcoholic $\text{KOH}$ ($\text{CHCl}_3 + \text{KOH}, \Delta$), producing an isocyanide (carbylamine) with an offensive odor: $\text{R-NH}_2 + \text{CHCl}_3 + 3\text{KOH} \xrightarrow{\Delta} \text{R-NC} + 3\text{KCl} + 3\text{H}_2\text{O}$
   • Secondary amines do not give this test.
   • Hence, A matches with II.

2. B. Acetaldehyde + Acetone

   • Acetaldehyde ($\text{CH}_3\text{CHO}$) is an aldehyde, whereas acetone ($\text{CH}_3\text{COCH}_3$) is a ketone.
   • Aldehydes reduce Tollens' reagent (ammoniacal silver nitrate, $[\text{Ag}(\text{NH}_3)_2]^+$) to form a shiny silver mirror: $\text{CH}_3\text{CHO} + 2[\text{Ag}(\text{NH}_3)_2]^+ + 3\text{OH}^- \rightarrow \text{CH}_3\text{COO}^- + 2\text{Ag}\downarrow + 4\text{NH}_3 + 2\text{H}_2\text{O}$
   • Simple ketones like acetone do not reduce Tollens' reagent.
   • Hence, B matches with IV.

3. C. Ethanol + Phenol

   • Phenol ($\text{C}_6\text{H}_5\text{OH}$) possesses an aromatic hydroxyl group that reacts with neutral ferric chloride ($\text{FeCl}_3$) to form a characteristic violet-colored complex: $6\text{C}_6\text{H}_5\text{OH} + \text{FeCl}_3 \rightarrow [\text{Fe}(\text{OC}_6\text{H}_5)_6]^{3-} + 3\text{H}^+ + 3\text{HCl}$
   • Aliphatic alcohols such as ethanol ($\text{C}_2\text{H}_5\text{OH}$) do not produce any such characteristic color change with neutral $\text{FeCl}_3$.
   • Hence, C matches with III.

4. D. Benzoic acid + Cinnamic acid

   • Cinnamic acid ($\text{C}_6\text{H}_5\text{CH}=\text{CHCOOH}$) contains an unsaturated carbon-carbon double bond ($>\text{C}=\text{C}<$) in its side chain.
   • It readily undergoes an addition reaction with bromine water ($\text{Br}_2/\text{H}_2\text{O}$), decolorizing the reddish-brown bromine solution.
   • Benzoic acid ($\text{C}_6\text{H}_5\text{COOH}$) lacks an aliphatic double bond and does not decolorize bromine water.
   • Hence, D matches with I.

Comparing with the given options: $\text{A} \rightarrow \text{II}, \quad \text{B} \rightarrow \text{IV}, \quad \text{C} \rightarrow \text{III}, \quad \text{D} \rightarrow \text{I}$

This sequence corresponds to Option D.