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Isomerism

JEE Main 2026 (Online) 2nd April Morning ShiftNumericalHard📈 Topic in 17% papers+4
Ques. 1JEE Main 2026, 2 April (Morning Shift)

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 .

Answer

14

Solution

C5H10 (one degree of unsaturation) that does not decolourise KMnO4 ⇒ no C=C ⇒ the isomers are cycloalkanes.

Number of monochloro products = number of different kinds of hydrogen (structural isomers only):

[figure]

Cyclopentane: all 10 H equivalent ⇒ 1

Methylcyclobutane: CH3, ring C-1, C-2 (= C-4), C-3 ⇒ 4

Ethylcyclopropane: CH3, CH2, ring C-1, C-2 (= C-3) ⇒ 4

1,1-Dimethylcyclopropane: CH3 (both same), ring CH2 ⇒ 2

1,2-Dimethylcyclopropane: CH3, ring C-1 (= C-2), ring C-3 ⇒ 3

∴ Total = 1 + 4 + 4 + 2 + 3 = 14

Answer: 14

Keep practising — Isomerism

Ques. 2JEE Main 2026, 24 January (Evening Shift)

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
Ques. 3JEE Main 2026, 23 January (Morning Shift)

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 .

Ques. 4JEE Main 2026, 21 January (Morning Shift)

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
Ques. 5JEE Main 2026, 21 January (Evening Shift)

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
Ques. 6JEE Main 2026, 21 January (Evening Shift)

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
Ques. 7JEE Main 2026, 21 January (Evening Shift)

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
Ques. 8JEE Main 2025, 7 April (Evening Shift)

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
Ques. 9JEE Main 2025, 7 April (Evening Shift)

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
Ques. 10JEE Main 2025, 3 April (Morning Shift)

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

  1. B & C Only
  2. C & D Only
  3. A,B & C Only
  4. A & B Only
Ques. 11JEE Main 2025, 3 April (Evening Shift)

The total number of structural isomers possible for the substituted benzene derivatives with the molecular formula C9H12 is .

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