Assertion (A) & Reason (B) MCQ

MCQ 11 Mark

Assertion $(A):$ Dehydration of glycerol with $\ce{KHSO_4}$ gives acrolein.
Reason $(R):$ Acrolein is an $\alpha ,$ $\beta-$unsaturated aldehyde.

✓
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 $A.$
C
$A$ is true but $R$ is false.
D
$A$ is false but $R$ is true.

Answer

Correct option: A.

Both $A$ and $R$ are true and $R$ is the correct explanation of $A.$

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MCQ 21 Mark

Assertion (A): Ammonolysis of alkyl halides is not a suitable method for the preparation of pure primary amines.
Reason (R): Ammonolysis of alkyl halides yields mainly secondary amines.

A
Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct
B
Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
✓
Assertion (A) is true, but Reason (R) is false
D
Assertion (A) is false, but Reason (R) is true.

Answer

Correct option: C.

Assertion (A) is true, but Reason (R) is false

(c) Assertion (A) is true, but Reason (R) is false.
Explanation: The amine formed reacts further with more of alkyl halide to give 2º and 3º amines and finally quaternary salt

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MCQ 31 Mark

Assertion (A): Aldehydes and ketones show condensation reactions.
Reason (R): The hydrogen atoms attached to $\alpha$-carbon of aldehydes and ketones are reactive.

✓
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.
C
A is true but R is false.
D
A is false but R is true.

Answer

Correct option: A.

Both A and R are true and R is the correct explanation of A.

(a) Both A and R are true and R is the correct explanation of A.
Explanation: The release of hydrogen from $\alpha$-carbon of aldehydes or ketones results in the formation of carbanion which is resonance stabilised. It is called enolate. Enolate ion can act as as a nucleophile and can attack the carbonyl group of the other molecule, i.e. giving condensation reactions.

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MCQ 41 Mark

Assertion (A): Cellulose can be easily converted into fibres.
Reason (R): Cotton contains about 90% cellulose.

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: Cellulose is a linear condensation polymer of β-glucose. Because of linear structure, cellulose can be easily converted into fibres.

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Chemistry Assertion (A) & Reason (B) MCQ

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