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Aldehydes, Ketones and Carboxylic Acids · Question 28

JEE Main 2025 (Online) 7th April Evening ShiftMCQMedium📈 Topic in 13% papers+4−1
1

"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]

Answer

(2) [figure]

Solution

Positive 2,4-DNP test P is an aldehyde or a ketone.

Negative Tollens' test P is not an aldehyde P is a ketone. This rules out option (1) (an aldehyde).

Optically active P has a chiral carbon.

Option (2): 3-methylpentan-2-one, C6H12O; C-3 carries H, CH3, C2H5 and COCH3 — four different groups chiral.

Option (3): hexan-2-one — no chiral carbon.

Option (4): 4-methylpentan-2-one — C-4 carries two CH3 groups, not chiral.

P is 3-methylpentan-2-one.

Answer: (2)

JEE Main 2025 (Online) 7th April Evening Shift

Keep practising — Aldehydes, Ketones and Carboxylic Acids

2

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
3

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
4

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
5

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
6

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
7

Consider the following molecules: [figure] The correct order of rate of hydrolysis is :

  1. p > q > r > s
  2. r > q > p > s
  3. p > r > q > s
  4. q > p > r > s
JEE Main 2025 (Online) 2nd April Morning Shift
8

Consider the following reactions. From these reactions which reaction will give carboxylic acid as a major product? Choose the correct answer from the options given below:

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

The product (P) formed in the following reaction is : [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 29th January Morning Shift
10

[figure] 0.1 mole of compound 'S' will weigh g. (Given molar mass in g mol-1 C : 12, H : 1, O : 16)

JEE Main 2025 (Online) 29th January Morning Shift
11

Both acetaldehyde and acetone (individually) undergo which of the following reactions? Choose the correct answer from the options given below:

  1. C and E Only
  2. A, B and D Only
  3. A, C and E Only
  4. B, C and D Only
JEE Main 2025 (Online) 28th January Morning Shift

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Inorganic ChemistryClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular Structurep-Block Elements (Group 13 & 14)p-Block Elements (Group 15–18)d- and f-Block ElementsCoordination Compounds
Organic ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIsomerismHydrocarbonsHaloalkanes and HaloarenesAlcohols, Phenols and EthersAldehydes, Ketones and Carboxylic AcidsAminesBiomoleculesPrinciples Related to Practical Chemistry