Assertion (A) & Reason (B) MCQ

MCQ 11 Mark

Direction in the following Questions, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following :
Assertion : The molecular orbitals with higher energy is called anti bonding orbitals.
Reason : The anti bonding nature of a molecular orbital is indicated by an asterisk over its designation.

✓
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B
Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
C
Assertion is true but Reason is false.
D
Both Assertion and Reason are false.

Answer

Correct option: A.

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

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MCQ 21 Mark

Direction in the following Questions, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following :
Assertion : Ionic compounds usually have high melting and boiling points.
Reason : A large amount of energy is needed to overcome the strong interionic electrostatic attractive forces.

✓
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B
Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
C
Assertion is true but Reason is false.
D
Both Assertion and Reason are false.

Answer

Correct option: A.

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

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MCQ 31 Mark

Note : In the following questions a statement of Assertion $(A)$ followed by a statement of Reason $(R)$ is given. Choose the correct option out of the choices given below each question.
Assertion $(A)$ : Among the two $O–H$ bonds in $\mathrm{H}_2\mathrm{O}$ molecule, the energy required to break the first $O – H$ bond and other $O – H $ bond is the same.
Reason $(R)$ : This is because the electronic environment around oxygen is the same even after breakage of one $O – H$ bond.

A
Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$
B
$A$ is true but $R$ is false.
C
$A$ is false but $R$ is true.
✓
Both $A$ and $R$ are false.

Answer

Correct option: D.

Both $A$ and $R$ are false.

The bond enthalphy in $H-O$ is not same for both the $O-H$ bonds. because electronic charge atom is different one $O-H$ bond.

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MCQ 41 Mark

Note : In the following questions a statement of Assertion $(A)$ followed by a statement of Reason $(R)$ is given. Choose the correct option out of the choices given below each question.
Assertion $(A)$ : Sodium chloride formed by the action of chlorine gas on sodium metal is a stable compound.
Reason $(R)$ : This is because sodium and chloride ions acquire octet in sodium chloride formation.

✓
$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$
B
$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.
C
$A$ is true but $R$ is false.
D
$A$ and $R$ both are false.

Answer

Correct option: A.

$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$

Sodium chloride $\left(\mathrm{Na}^{+} \mathrm{Cl}^{-}\right)$ is stable ionic compound because both $\mathrm{Na}^{+}$and $\mathrm{Cl}^{-}$ ions have complete octate in outermost shell.

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MCQ 51 Mark

Note : In the following questions a statement of Assertion $(A)$ followed by a statement of Reason $(R)$ is given. Choose the correct option out of the choices given below each question.
Assertion $(A)$ : Though the central atom of both $\mathrm{NH}_3$ and $\mathrm{H}_2 \mathrm{O}$ molecules are $\mathrm{sp}^3$ hybridised, yet $\mathrm{H}-\mathrm{N}-\mathrm{H}$ bond angle is greater than that of $\mathrm{H}-\mathrm{O}-\mathrm{H}$.
Reason $(R)$ : This is because nitrogen atom has one lone pair and oxygen atom has two lone pairs.

✓
$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$
B
$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.
C
$A$ is true but $R$ is false.
D
$A$ and $R$ both are false.

Answer

Correct option: A.

$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$

$\mathrm{H}_2 \mathrm{O}$ has two lone pairs while $\mathrm{NH}_3$ has single lone pair, hence, $\mathrm{H}_2 \mathrm{O}$ involves greater lone pair-bond pair repulsion.

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Chemistry Assertion (A) & Reason (B) MCQ

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