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Aldehydes, Ketones and Carboxylic Acids · Question 23

JEE Main 2026 (Online) 21st January Morning ShiftMCQMedium📈 Topic in 13% papers+4−1
1

An organic compound "P" of molecular formula C6H12O3 gives positive iodoform test but negative Tollens' test. When "P" is treated with dilute acid, it produces "Q". "Q" gives positive Tollens' test and also iodoform test. The structure of "P" is :

  1. H- O \|C-CH2-CH2- OCH3 |CH-OCH3
  2. CH3- O \|C- OCH3 |CH- OCH3 |CH2
  3. CH3- O \|C-CH2- OCH3 |CH-OCH3
  4. CH3- O \|C- OCH3 | OCH3 |C-CH3

Answer

(3) CH3- O \|C-CH2- OCH3 |CH-OCH3

Solution

P gives a positive iodoform test P contains CH3-CO-.

P gives a negative Tollens' test P has no free –CHO group.

Q (formed by dilute acid) gives a positive Tollens' test a –CHO group is set free on hydrolysis P contains an acetal group, -CH(OCH3)2.

For option (3): CH3COCH2CH(OCH3)2 ( C6H12O3 ✓)

CH3COCH2CH(OCH3)2 + H2O H+ CH3COCH2CHO + 2CH3OH

Q = CH3COCH2CHO has –CHO (Tollens' test positive) and CH3CO- (iodoform test positive). ✓

(1) has a free –CHO group (Tollens' test positive) and no CH3CO- group.

(2) contains only ether linkages, which are not hydrolysed by dilute acid no aldehyde is formed.

(4) is a ketal; hydrolysis gives CH3COCOCH3, a diketone with no –CHO group.

Answer: (3)

JEE Main 2026 (Online) 21st January Morning Shift

Keep practising — Aldehydes, Ketones and Carboxylic Acids

2

Match List - I with List - II. Choose the correct answer from the options given below :

  1. A-II, B-III, C-IV, D-I
  2. A-IV, B-III, C-I, D-II
  3. A-IV, B-I, C-II, D-III
  4. A-II, B-IV, C-I, D-III
JEE Main 2026 (Online) 21st January Evening Shift
3

A [(ii) H3O+](i) NaOH B [(ii) H2SO4, ](i) EtOH C 'A' shows positive Lassaigne's test for N and its molar mass is 121. 'B' gives effervescence with aq NaHCO3. 'C' gives fruity smell. Identify A, B and C from the following.

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 8th April Evening Shift
4

When [figure] undergoes intramolecular aldol condensation, the major product formed is :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 8th April Evening Shift
5

Which of the following compounds is least likely to give effervescence of CO2 in presence of aq. NaHCO3?

  1. Ph- NH3 Cl
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 7th April Morning Shift
6

"P" is an optically active compound with molecular formula C6H12O. When "P" is treated with 2,4-dinitrophenylhydrazine, it gives a positive test. However, in presence of Tollens' reagent, "P" gives a negative test. Predict the structure of "P".

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 7th April Evening Shift
7

Aldol condensation is a popular and classical method to prepare , -unsaturated carbonyl compounds. This reaction can be both intermolecular and intramolecular. Predict which one of the following is not a product of intramolecular aldol condensation?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 4th April Morning Shift
8

Which among the following compounds give yellow solid when reacted with NaOI/NaOH? Choose the correct answer from the options given below :

  1. (A) and (C) Only
  2. (C) and (D) Only
  3. (B), (C) and (E) Only
  4. (A), (C) and (D) Only
JEE Main 2025 (Online) 4th April Evening Shift
9

Number of molecules from below which cannot give iodoform reaction is : Ethanol, Isopropyl alcohol, Bromoacetone, 2-Butanol, 2-Butanone, Butanal, 2-Pentanone, 3-Pentanone, Pentanal and 3-Pentanol.

  1. 4
  2. 3
  3. 5
  4. 2
JEE Main 2025 (Online) 3rd April Morning Shift
10

The major product (P) in the following reaction is : Ph- O \|C- O \|C-H [ ]KOH Major ProductP

  1. Ph- O \|C-COO K
  2. Ph- OH |CH-CH2OH
  3. Ph- OH |CH-COO K
  4. Ph- O \|C-CH2OH
JEE Main 2025 (Online) 3rd April Evening Shift
11

Given below are two statements: In the light of the above statements, choose the most appropriate answer from the options given below :

  1. Statement I is correct but Statement II is incorrect
  2. Both Statement I and Statement II are correct
  3. Both Statement I and Statement II are incorrect
  4. Statement I is incorrect but Statement II is correct
JEE Main 2025 (Online) 2nd April Morning Shift

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