PYQSide ExamsMy practice

Isomerism · Question 3

JEE Main 2026 (Online) 2nd April Morning ShiftNumericalHard📈 Topic in 23% papers+4
1

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

JEE Main 2026 (Online) 2nd April Morning Shift

Keep practising — Isomerism

2

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
3

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
4

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
5

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
6

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
7

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
8

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
9

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
10

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
JEE Main 2025 (Online) 3rd April Morning Shift
11

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

JEE Main 2025 (Online) 3rd April Evening Shift

All Isomerism PYQs →

PDFDownload Isomerism PYQs as PDF Free, with answer key and a QR code to every solution — print it or study offline⬇
All JEE Main Chemistry chapters
Physical ChemistrySome Basic Concepts of ChemistryStructure of AtomStates of MatterThermodynamicsEquilibriumRedox ReactionsSolutionsElectrochemistryChemical Kinetics
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