Assertion (A) & Reason (B) MCQ

MCQ 11 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 $(A)$ : The ionisation of hydrogen sulphide in water is low in the presence of hydrochloric acid.
Reason $(R)$ : Hydrogen sulphide is a weak acid.

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

$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.

In presence of $H^{+}$ ion, equilibrium shifts in backward direction.

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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 : A solution containing a mixture of acetic acid and sodium acetate maintains a constant value of $\ce{pH}$ on addition of small amounts of acid or alkali.
Reason : A solution containing a mixture of acetic acid and sodium acetate acts as a buffer solution around $\ce{pH}\ 4.75.$

✓
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 $(A)$ : A solution containing a mixture of acetic acid and sodium acetate maintains a constant value of $\ce{pH}$ on addition of small amounts of acid or alkali.
Reason $(R)$ : A solution containing a mixture of acetic acid and sodium acetate acts as a buffer solution around $\ce{pH}\ 4.75.$

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

$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.

The solutions which resist change in $\ce{pH}$ on dilution or with the addition of small amounts of acid or alkali are called buffer solutions.

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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 $(A)$ : An aqueous solution of ammonium acetate can act as a buffer.
Reason $(R)$ : Acetic acid is a weak acid and $\ce{NH_4OH}$ is a weak base.

A
$A$ 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 $A$.
✓
$A$ is true but $R$ is false.
D
$A$ and $R$ both are false.

Answer

Correct option: C.

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

Salt of weak acid and weak base can form buffer solution.

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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 $(A)$ : In the dissociation of $\mathrm{PCl}_5$ at constant pressure and temperature addition of helium at equilibrium increases the dissociation of $\mathrm{PCl}_5$.
Reason $(R)$ : Helium removes $\mathrm{Cl}_2$ from the field of action.

A
Both $A$ and $R$ are true and $R$ is correct explanation of $A.$
B
Both $A$ and $R$ are true but $R$ is not 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.

If the volume is kept constant and an inert gas such as argon is added which does not take part in the reaction, the equilibrium remains undisturbed.

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MCQ 61 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 $(A)$ : Increasing order of acidity of hydrogen halides is.
$\ce{HF < HCl < HBr < HI}$
Reason $(R)$ : While comparing acids formed by the elements belonging to the same group of periodic table, $H -$ A bond strength is a more important factor in determining acidity of an acid than the polar nature of the bond.

✓
$A$ 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 $A.$

$\frac{\text{H}-\text{F} < \text{H}-\text{Cl}<\text{H}-\text{Br} < \text{H}-\text{I}}{\text{Increasing acidic character}}$
Weaker is the covalent bond, stronger is the acidic character.

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MCQ 71 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 $(A)$ : Aqueous solution of ammonium carbonate is basic.
Reason $(R)$ : Acidic/ basic nature of a salt solution of a salt of weak acid and weak base depends on $\mathrm{K}_{\mathrm{a}}$ and $\mathrm{K}_{\mathrm{b}}$ value of the acid and the base forming it.

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

Answer

Correct option: A.

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

$\mathrm{K}_{\mathrm{a}}$ and $\mathrm{K}_{\mathrm{b}}$ values are responsible for acidic and basic characters of substances.

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MCQ 81 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 $(A)$ : For any chemical reaction at a particular temperature, the equilibrium constant is fixed and is a characteristic property.
Reason $(R)$ : Equilibrium constant is independent of temperature.

A
$A$ 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 $A$.
✓
$A$ is true but $R$ is false.
D
$A$ and $R$ both are false.

Answer

Correct option: C.

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

The equilibrium constant for an exothermic reaction $($negative $\Delta\text{H})$ decreases as the temperature increases.
The equilibrium constant for an endothermic reaction $($positive $\Delta\text{H})$ increases as the temperature increases.

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MCQ 91 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 : Increasing order of acidity of hydrogen halides is $\ce{HF < HCl < HBr < HI}$
Reason : While comparing acids formed by the elements belonging to the same group of periodic table, $H-A$ bond strength is a more important factor in determining acidity of an acid than the polar nature of the bond.

✓
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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Chemistry Assertion (A) & Reason (B) MCQ

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