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Isomerism · Question 1

JEE Main 2026 (Online) 6th April Morning ShiftMCQMedium📈 Topic in 23% papers+4−1
1

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

  1. Both Statement I and Statement II are true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true

Answer

(3) Statement I is true but Statement II is false

Solution

Statement I:

[figure]

Both are C10H18O cyclohexanones with the same functional group, but the alkyl groups on the two α-carbons differ (ethyl / ethyl and methyl / n-propyl)

⇒ they are metamers ⇒ Statement I is true.

Statement II:

[figure]

Keto–enol tautomerism needs at least one α-hydrogen. Both α-carbons (C-2 and C-6) carry two methyl groups and no H

⇒ no enol can form ⇒ Statement II is false.

Answer: (3)

JEE Main 2026 (Online) 6th April Morning Shift

Keep practising — Isomerism

2

The following structures are : [figure]

  1. enantiomers.
  2. identical molecules.
  3. diastereomers.
  4. meso compounds.
JEE Main 2026 (Online) 4th April Evening Shift
3

Consider the isomers of hydrocarbon with molecular formula C5H10. These isomers do not decolourise KMnO4 solution. These isomers are subjected to chlorination with chlorine in presence of light to give monochloro compounds. The total number of monochloro compounds (structural isomers only) formed is .

JEE Main 2026 (Online) 2nd April Morning Shift
4

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

  1. Statement I is false but Statement II is true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Both Statement I and Statement II are true
JEE Main 2026 (Online) 24th January Evening Shift
5

Consider all the structural isomers with molecular formula C5H11Br are separately treated with KOH(aq) to give respective substitution products, without any rearrangement. The number of products which can exhibit optical isomerism from these is .

JEE Main 2026 (Online) 23rd January Morning Shift
6

Identify correct statements from the following : Choose the correct answer from the options given below :

  1. A, B and E only
  2. A, B and C only
  3. C, D and E only
  4. B, C and D only
JEE Main 2026 (Online) 21st January Morning Shift
7

In the light of the above statements, choose the correct answer from the options given below :

  1. Statement I is true but Statement II is false
  2. Both Statement I and Statement II are true
  3. Both Statement I and Statement II are false
  4. Statement I is false but Statement II is true
JEE Main 2026 (Online) 21st January Evening Shift
8

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

  1. A-III, B-I, C-IV, D-II
  2. A-II, B-I, C-IV, D-III
  3. A-I, B-IV, C-III, D-II
  4. A-III, B-I, C-II, D-IV
JEE Main 2026 (Online) 21st January Evening Shift
9

Given below are four compounds : (a) n-propyl chloride (b) isopropyl chloride (c) sec-butyl chloride (d) neopentyl chloride Percentage of carbon in the one which exhibits optical isomerism is :

  1. 46
  2. 40
  3. 52
  4. 56
JEE Main 2026 (Online) 21st January Evening Shift
10

The number of optically active products obtained from the complete ozonolysis of the given compound is : [figure]

  1. 4
  2. 0
  3. 2
  4. 1
JEE Main 2025 (Online) 7th 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. Both Statement I and Statement II are correct
  2. Statement I is incorrect but Statement II is correct
  3. Both Statement I and Statement II are incorrect
  4. Statement I is correct but Statement II is incorrect
JEE Main 2025 (Online) 7th April Evening Shift

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