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 decomposition of hydrogen peroxide to form water and oxygen is an example of disproportionation reaction.
Reason $(R)$ : The oxygen of peroxide is in $–1$ oxidation state and it is converted to zero oxidation state in $\mathrm{O}_2$ and –2 oxidation state in $\mathrm{H}_2 \mathrm{O}$.

✓
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
Both $A$ and $R$ are false.

Answer

Correct option: A.

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

$2\text{H}_2\text{O}_2\text{(ag)}\xrightarrow{ \ \ \ \ \ \ \ \ }2\text{H}_2\text{O(l)}+\text{O}_2\text{(g)}$
Here the oxygen of peroxide, which is present in $-1$ state, is converted to zero oxidation state in $\mathrm{O}_2$ undergoing oxidation and decreases to $-2$ oxidation state in $\mathrm{H}_2 \mathrm{O}$ undergoing reduction.

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MCQ 21 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 reaction between potassium permanganate and potassium iodide, permanganate ions act as oxidising agent.
Reason $(R)$ : Oxidation state of manganese changes from $+2$ to $+7$ during the reaction.

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.

As permanganate ion changes to $\mathrm{MnO}_2$.

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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 $(A)$ : Redox couple is the combination of oxidised and reduced form of a substance involved in an oxidation or reduction half cell.
Reason $(R)$ : In the representation $\text{E}^\ominus_{\text{Fe}^{3+}/\text{Fe}^{2+}}$ and $\text{E}^\ominus_{\text{Cu}^{2+}/\text{Cu}},\text{Fe}^{3+}/\text{Fe}^{2+}$ and $\text{Cu}^{2+}/\text{Cu}$ are redox couples.

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 $A$.

A redox couple is defined as pair of compounds or elements having together the oxidised and reduced forms of it and taking part in an oxidation or reduction half reaction.

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MCQ 41 Mark

✓
$A$ 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 $A.$

Fluorine is most electronegative element that is why it is best oxidant among halogens.

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Chemistry Assertion (A) & Reason (B) MCQ

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