Match List I with List II

Choose the correct answer from the options given below:

A-III, B-IV, C-II, D-I

The correct answer is option 1. A-III, B-IV, C-II, D-I.

Let us break down each reagent in List I and match it with its corresponding description from List II, with detailed explanations.

(A) Tollen’s Reagent – (III) Ammoniacal Silver Nitrate

Tollen’s reagent is used primarily for detecting aldehydes. It is a solution of silver nitrate (\(AgNO_3\)) in ammonia (NH₃), forming a complex ion known as ammoniacal silver nitrate (\([Ag(NH_3)_2]^+\)). This reagent is unique in that it selectively oxidizes aldehydes to carboxylic acids. The distinguishing feature of Tollen's test is the formation of a silver mirror on the walls of the test tube when an aldehyde is present. This happens because aldehydes reduce the silver ion \((Ag^+)\) to metallic silver \((Ag^0)\).

Match: Tollen's reagent → Ammoniacal silver nitrate \( A \to (III) \)

(B) Jones Reagent – (IV) Chromium Tetroxide in Sulfuric Acid

Jones reagent is a powerful oxidizing agent, consisting of chromium trioxide (\(CrO_3\)) dissolved in aqueous sulfuric acid. It is used to oxidize primary alcohols to carboxylic acids and secondary alcohols to ketones. The reagent contains chromium in the +6 oxidation state (as \(CrO_3\)), which is reduced to chromium in the +3 oxidation state during the oxidation of alcohols. Jones reagent is highly effective in organic chemistry for oxidation reactions and is frequently used when a strong oxidizer is required.

Match: Jones reagent → Chromium trioxide in sulfuric acid \( B \to (IV) \)

(C) Lucas Reagent – (II) Concentrated HCl and Zinc Chloride

Lucas reagent is a mixture of concentrated hydrochloric acid (HCl) and anhydrous zinc chloride (ZnCl₂). It is used to classify alcohols based on their reactivity with the reagent. Specifically, it distinguishes between primary, secondary, and tertiary alcohols by the time it takes for a cloudy layer or phase separation to form. Tertiary alcohols react quickly, producing an insoluble alkyl chloride almost immediately. Secondary alcohols react more slowly, forming a cloudy mixture after a few minutes. Primary alcohols typically do not react at room temperature.

Match: Lucas reagent → Concentrated HCl and \(ZnCl_2\) \( C \to (II) \)

(D) Fehling’s Solution – (I) Rochelle Salt

Fehling's solution is a classical reagent used to detect reducing sugars, such as glucose. It consists of two separate solutions:

Fehling's A: Aqueous copper(II) sulfate (CuSO₄).

Fehling's B: An alkaline solution of sodium potassium tartrate, also known as Rochelle salt. The tartrate ion complexes with the copper(II) ions, preventing their precipitation in the basic medium.

When a reducing sugar is present, the copper(II) ions are reduced to copper(I) oxide (Cu₂O), which precipitates as a red solid, indicating a positive test.

Match: Fehling’s solution → Rochelle salt \( D \to (I) \)

The correct answer is 1. A-III, B-IV, C-II, D-I.