Practicing Success

Target Exam

CUET

Subject

Chemistry

Chapter

Organic: Aldehydes, Ketones and Carboxylic Acids

Question:

Match List I with List II

List I List II
(A) Tollen's Reagent (I) Rochelle salt
(B) Jones Reagent (II) conc HCl and \(ZnCl_2\)
(C) Lucas reagent (III) Ammonical silver nitrate
(D) Fehling Solution (IV) Chromium tetroxide sulphuric acid

Choose the correct answer from the options given below:

Options:

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

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

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

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

Correct Answer:

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

Explanation:

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

List I List II
(A) Tollen's Reagent (III) Ammonical silver nitrate
(B) Jones Reagent (IV) Chromium tetroxide sulphuric acid
(C) Lucas reagent (II) conc HCl and \(ZnCl_2\)
(D) Fehling Solution (I) Rochelle salt

Let us explain each matching:

(A) Tollen's Reagent: (III) Ammonical silver nitrate

Tollen's Reagent is used to distinguish between aldehydes and ketones. It is a solution of silver ions in aqueous ammonia. In the presence of an aldehyde, Tollen's Reagent undergoes a redox reaction, where silver ions are reduced to form a silver mirror on the inner surface of the reaction vessel. This reaction is used as a qualitative test for the presence of aldehydes.

(B) Jones Reagent:(IV) Chromium tetroxide sulphuric acid

Jones Reagent is a mixture of chromium trioxide (\(CrO_3\)) and concentrated sulfuric acid (\(H_2SO_4\)). It is used as a powerful oxidizing agent in organic synthesis to convert primary and secondary alcohols to their corresponding aldehydes and ketones, respectively.

(C) Lucas reagent corresponds to: (II) conc HCl and \(ZnCl_2\)

Lucas reagent is a solution of concentrated hydrochloric acid (\(HCl\)) containing zinc chloride (\(ZnCl_2\)). It is used to distinguish between primary, secondary, and tertiary alcohols. Tertiary alcohols react rapidly with Lucas reagent to form a cloudy solution, whereas secondary alcohols react more slowly, and primary alcohols do not react at all under normal conditions.

(D) Fehling Solution: (I) Rochelle salt

Fehling Solution is used to distinguish between aldehydes and ketones. It is a mixture of Fehling's A solution (aqueous copper(II) sulfate) and Fehling's B solution (aqueous potassium sodium tartrate, also known as Rochelle salt). In the presence of an aldehyde, Fehling Solution undergoes a redox reaction, where the aldehyde is oxidized to a carboxylic acid, and the copper(II) ions in Fehling's A solution are reduced to form a red precipitate of copper(I) oxide.

Each reagent in List I has a specific chemical composition and is used for distinct qualitative tests in organic chemistry.

Therefore, the correct explanation for the matching is 1. A-III, B-IV, C-II, D-I