Assertion (A) & Reason (B) MCQ

MCQ 11 Mark

Assertion $(A):$ Last traces of moisture in ethanol can be removed by keeping it over sodium wire
Reason $(R):$ Sodium reacts with water but not with ethanol to produce $H_2$ gas.

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
both $A$ and $R$ are false.

Answer

Correct option: C.

$A$ is true but $R$ is false.

Last traces of moisture in ethanol cannot be removed by keeping it over sodium wire. Sodium reacts both with $H_2O$ and ethanol.

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MCQ 21 Mark

Assertion (A): Aryl halide gives a mixture of o- and p-products.
Reason (R): Aryl halides undergo electrophilic substitutions more readily than benzene.

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: Halogens are somewhat deactivating but o, p-directing. As a result, aryl halides undergo the usual electrophilic substitution reactions less readily than benzene

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MCQ 31 Mark

Assertion $(A): \ce{RCHO, RCOCH_3}$ and cyclic ketones react with sodium bisulphite.
Reason $(R):$ Crystalline solid derivatives are formed when aldehydes or ketones are shaken with saturated aqueous solution of sodium bisulphite.

✓
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 $A.$

$\mathrm{SO}_3$ is a large ion. Its addition is possible only under the condition that

grouping is not sterically hindered as is the case for $\ce{RCHO, RCOCH_3}$ and cyclic ketones.

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MCQ 41 Mark

Assertion (A): Primary structure of proteins gives an idea about the conformation of the molecule.
Reason (R): The differences in chemical and biological properties of various proteins arise due to the difference in primary structure.

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

Answer

Correct option: D.

A is false but R is true.

(d) A is false but R is true.
Explanation: The primary structure of a protein gives only the nature of linkages of -amino acids in a protein chain.

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Chemistry Assertion (A) & Reason (B) MCQ

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