Assertion (A) & Reason (B) MCQ

Question 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 $109^\circ 28'.$

Answer

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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Question 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.

Answer

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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Question 31 Mark

Assertion (A): Benzaldehyde is less reactive than ethanal towards nucleophilic addition reactions.
Reason (R): Ethanal is more sterically hindered

Answer

(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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Question 41 Mark

Assertion (A): Cellulose is not digested by human beings.
Reason (R): Cellulose is a polymer of β-D-glucose.

Answer

(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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