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Isomerism (GATE)

Practice questions on conformational isomerism, geometrical isomerism, stereoisomerism, chirality, optical activity, and related organic chemistry concepts for GATE exam preparation.

15 Questions Published
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Questions

Question 1 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: The energy difference between staggered and eclipsed conformations of ethylene dichloride is less than in ethylene dibromide.
Reason: The bond moment of C-Cl is greater than that of C-Br.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 2 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: The compound C6H5CH=CHCl is called β-chlorostyrene.
Reason: In organic halides, the carbon atom is attached to the halogen atom designated as α.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 3 Multiple Choice (Single Answer)

Which of the following statements is/are correct?

A. 1-Chloro-2,3-pentadiene has no chiral carbon atoms, yet it is a chiral molecule.
B. A newly discovered compound is through to be chiral, but shows no rotation in a specific solvent. This means that the compound is assuredly achiral.
C. When a chiral molecule reacts to give a chiral molecule, the product is always racemic.

  1. Only A
  2. Only B
  3. Only C
  4. A and C
  5. B and C
Question 4 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.
Assertion: Cyclohexane floats over water.
Reason: Most of the molecules of cyclohexane assume boat conformation.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 5 Multiple Choice (Single Answer)

Which of the following statements is/are wrong?

A. 1-Methoxypropane and 2-methoxypropane are metamers.
B. An optically active substance must be achiral.
C. m-Chlorobromobenzene and m-bromochlorobenzene are isomers.

  1. A and B
  2. A and C
  3. B and C
  4. A, B and C
  5. Only A
Question 6 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: In CH2F2, the F-C-F bond angle is less than 109.5˚, indicating less than 25% s-character, but the H-C-H bond angle is larger and the C-H bond has more s-character.
Reason: More electronegative substituents prefer hybrid orbitals having less s-character and more electropositive substituents prefer hybrid orbitals having more s-character.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 7 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: Benzaldehyde forms two oximes on reacting with NH2OH.
Reason: The two oximes arise due to geometrical isomerism around C=N bond.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 8 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: 1,2-Propadiene exhibits optical isomerism.
Reason: Its mirror image is non-superimposable.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 9 Multiple Choice (Single Answer)

Which of the following statements is/are false?

A. Compounds containing one chiral carbon atom are always optically active.
B. Maleic acid and fumeric acid are geometrical isomers.
C. Maleic acid is less soluble in water than fumeric acid.

  1. Only A
  2. Only B
  3. Only C
  4. A, B and C
  5. A and B
Question 10 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: Propionic acid contains a prochiral carbon.
Reason: Replacement of hydrogen atom of the CH2 group by Br atom produces achiral carbon.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 11 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: CHBr = CHCl exhibits geometrical isomerism, but CH2Br-CH2Cl does not.
Reason: Presence of C=C is one of the conditions of geometrical isomerism.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 12 Multiple Choice (Single Answer)

Which of the following statements is/are true?

A. The dihedral angle between the H-atoms in staggered conformation of ethane is 60˚.
B. C2H5O2N shows functional isomerism as well as tautomerism.
C. Cyclopropane is a better fuel than propane.

  1. Only A
  2. Only B
  3. A and C
  4. A, B and C
  5. Only C
Question 13 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: Stereoisomers, which are not mirror images of each other, are called diastereomers.
Reason: Diastereomers may or may not be optically active.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 14 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.
Assertion: Both cyclopropane and propene give addition reactions readily.
Reason: Cyclopropane and propene are isomers of each other.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
Question 15 Multiple Choice (Single Answer)

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: All the carbon atoms in but-2-ene lie in one plane.
Reason: All the carbon atoms of but-2-ene are sp2-hybridised.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
  5. Both A and R are false.
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