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Isomerism

JEE Main 2026 (Online) 24th January Evening ShiftMCQEasy📈 Topic in 3% papers+4−1
Ques. 1JEE 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

Answer

(4) Both Statement I and Statement II are true

Solution

Statement I: In (X) the two CH3 groups (and the H atoms) eclipse each other, dihedral angle between the CH3 groups = 0 .

maximum torsional and steric strain (X) is the least stable conformer.

In (Y) the two CH3 groups are anti, dihedral angle = 180 .

minimum strain (Y) is the most stable conformer.

Statement I is true.

Statement II: As per NCERT, torsional strain is maximum in the eclipsed form and minimum in the staggered (anti) form. On going from (X) (0 ) to (Y) (180 ) the dihedral angle increases and the strain falls to its minimum (stability: anti > gauche > eclipsed).

Statement II is true.

Answer: (4)

Keep practising — Isomerism

Ques. 2JEE 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. 3JEE 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. 4JEE 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. 5JEE 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. 6JEE 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. 7JEE 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. 8JEE 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. 9JEE 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. 10JEE Main 2025, 3 April (Evening Shift)

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

Ques. 11JEE Main 2025, 28 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 true
  3. Statement I is true but Statement II is false
  4. Both Statement I and Statement II are false

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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