Question

Match the following (List–I with List–II) and choose the correct option.

• A. a(i), b(ii), c(iii), d(iv)
• B. a(iv), b(iii), c(ii), d(i)
• C. a(iii), b(ii), c(iv), d(i)
• D. a(i), b(ii), c(iv), d(iii)

Hint:

Always remember the medium of reduction:
\textbf{Acidic medium} → Zn–Hg/HCl (Clemmensen)
\textbf{Basic medium} → NH\(_2\)–NH\(_2\)/KOH (Wolff–Kishner)
\([\text{Ag}(\text{NH}_3)_2]^+\) → Tollen’s test
Cu\(^{2+}\)/OH\(^{-}\) → Fehling’s test

Answer 1

The Correct Option is C

Concept: This question tests knowledge of important qualitative reagents and named organic reactions. Each reagent in List–I has a well-known composition and specific use, which helps in direct identification.
Step 1: Analyze item (a). \[ [\text{Ag}(\text{NH}_3)_2]^+ \] This is the diamminesilver(I) complex. It is the active species present in Tollen’s reagent, which is used to test aldehydes and produces a silver mirror. \[ (a) \rightarrow \text{Tollen’s reagent} \rightarrow (iii) \]
Step 2: Analyze item (b). \[ \text{Zn–Hg / HCl} \] This reagent is used to reduce aldehydes and ketones to hydrocarbons under strongly acidic conditions. This reaction is known as Clemmensen’s reduction. \[ (b) \rightarrow \text{Clemmensen’s reduction} \rightarrow (ii) \]
Step 3: Analyze item (c). \[ \text{NH}_2\text{–NH}_2 / \text{KOH} \] Hydrazine in the presence of strong base converts aldehydes and ketones into hydrocarbons under basic conditions. This reaction is known as the Wolff–Kishner reduction. \[ (c) \rightarrow \text{Wolff–Kishner reduction} \rightarrow (iv) \]
Step 4: Analyze item (d). \[ \text{Cu}^{2+} / \text{OH}^- \] Alkaline copper(II) ions form the basis of Fehling’s solution, which is used to detect aliphatic aldehydes by forming a red precipitate of Cu\(_2\)O. \[ (d) \rightarrow \text{Fehling’s solution} \rightarrow (i) \]
Step 5: Write the complete matching. \[ a(iii),\; b(ii),\; c(iv),\; d(i) \] This corresponds to Option (3).