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Chemistry Assertion (A) & Reason (B) MCQ [1M]

MODEL PAPER 2 · Bihar Board (BSEB) STD 12 Science (BSEB - English Medium). 4 questions.

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Assertion (A) & Reason (B) MCQ [1M]

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4 questions · timed · auto-graded

MCQ 11 Mark
Assertion (A): The oxygen of OH group in alcohols is attached to sp3 hybridised carbon.
Reason (R): The bond angle in alcohols C-O-H is 109°28'.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • ✓
    A is true but R is false.
  • D
    A is false but R is true.
Answer
Correct option: C.
A is true but R is false.
(c) A is true but R is false.
Explanation:
The bond angle $C -\widehat{ O }- H$ in alcohols is slightly less than the tetrahedral angle 109°28'. It is due to the repulsion between the unshared electron pairs of oxygen.
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MCQ 21 Mark
Assertion (A): Hydrolysis of (-)-2-bromooctane proceeds with inversion of configuration.
Reason (R): This reaction proceeds through the formation of a carbocation to give (+)-octan-2-ol as a product. In SN2 reaction of optically active halides are accompanied by inversion of configuration.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • ✓
    A is true but R is false.
  • D
    A is false but R is true.
Answer
Correct option: C.
A is true but R is false.
(c) A is true but R is false.
Explanation: Hydrolysis of alkyl halides with inversion of configuration is an example of SN2 mechanism. This mechanism is a one-step process and does not involve the formation of a carbocation.
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MCQ 31 Mark
Assertion (A): Benzaldehyde is less reactive than ethanal towards nucleophilic addition reactions.
Reason (R): Ethanal is more sterically hindered
  • A
    Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
  • B
    Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
  • ✓
    Assertion (A) is correct, but Reason (R) is wrong statement.
  • D
    Assertion (A) is wrong, but Reason (R) is correct statement.
Answer
Correct option: C.
Assertion (A) is correct, but Reason (R) is wrong statement.
(c) Assertion (A) is correct, but Reason (R) is wrong statement.
Explanation: Assertion (A) is correct, but Reason (R) is wrong statement.
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MCQ 41 Mark
Assertion (A): Cellulose is not digested by human beings.
Reason (R): Cellulose is a polymer of β-D-glucose.
  • A
    Both A and R are true and R is the correct explanation of A.
  • ✓
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true
Answer
Correct option: B.
Both A and R are true but R is not the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
Explanation: Both A and R are true but R is not the correct explanation of A.
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Assertion (A) & Reason (B) MCQ [1M] - Chemistry STD 12 Science Questions - Vidyadip