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Isomerism

JEE Main 2025 (Online) 3rd April Evening ShiftNumericalMedium📈 Topic in 17% papers+4
Ques. 1JEE Main 2025, 3 April (Evening Shift)

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

Answer

8

Solution

C9H12 = C6H6 ring + 3 more C atoms (all saturated, DBE = 4 is used up by the benzene ring).

(i) One substituent (-C3H7): 2 isomers

[figure]

(ii) Two substituents (-C2H5 and -CH3): 3 isomers

[figure]

(iii) Three -CH3 groups: 3 isomers

[figure]

total structural isomers = 2 + 3 + 3 = 8

Answer: 8

Keep practising — Isomerism

Ques. 2JEE 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
Ques. 3JEE Main 2025, 24 January (Evening Shift)

The possible number of stereoisomers for 5-phenylpent-4-en-2-ol is .

Ques. 4JEE Main 2025, 22 January (Morning Shift)

How many different stereoisomers are possible for the given molecule? [figure]

  1. 2
  2. 1
  3. 3
  4. 4
Ques. 5JEE Main 2025, 22 January (Morning Shift)

The incorrect statements regarding geometrical isomerism are : Choose the correct answer from the options given below :

  1. A and E Only
  2. A, D and E Only
  3. C, D and E Only
  4. B and C Only
Ques. 6JEE Main 2024, 9 April (Evening Shift)

Total number of stereo isomers possible for the given structure : [figure]

  1. 4
  2. 2
  3. 8
  4. 3
Ques. 7JEE Main 2024, 8 April (Morning Shift)

The number of optical isomers in following compound is : . [figure]

Ques. 8JEE Main 2024, 8 April (Evening Shift)

The number of optically active compounds from the following is . [figure] CH3-CH2-CH2-CH2-OH, CH3-CH2- Cl |CH-CH3, CH3-CH2-CH2-CH2-Cl, (CH3)2CH-CH2-CH2-Cl

Ques. 9JEE Main 2024, 6 April (Morning Shift)

Which of the following is metamer of the given compound (X) ? [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 10JEE Main 2024, 6 April (Evening Shift)

The incorrect statement regarding the geometrical isomers of 2-butene is :

  1. cis-2-butene and trans-2-butene are not interconvertible at room temperature.
  2. trans-2-butene is more stable than cis-2-butene.
  3. cis-2-butene has less dipole moment than trans-2-butene.
  4. cis-2-butene and trans-2-butene are stereoisomers.
Ques. 11JEE Main 2024, 5 April (Morning Shift)

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the correct answer from the options given below :

  1. (A) is true but (R) is false
  2. (A) is false but (R) is true
  3. Both (A) and (R) are true and (R) is the correct explanation of (A)
  4. Both (A) and (R) are true but (R) is NOT the correct explanation of (A)

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