Assertion (A) & Reason (B) MCQ

MCQ 11 Mark

Assertion $(A):$ The oxygen of $OH$ group in alcohols is attached to $sp^3$ hybridised carbon.
Reason $(R): $ The bond angle in alcohols $C-O-H$ is $109^\circ \ 28 \ '.$

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 $A.$

The bond angle $C -\widehat{ O }- H$ in alcohols is slightly less than the tetrahedral angle $109^\circ \ 28 \ '.$ 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 $S_N2$ 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.

Hydrolysis of alkyl halides with inversion of configuration is an example of $S_N2$ 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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Chemistry Assertion (A) & Reason (B) MCQ

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