Assertion :- Equivalent weight of `KMnO_(4)` in acidic medium is `M//5` (M=molecular weight) while in basic medium, it is equal of M/3.
Reason :- In acidic medium, 1 mol of `MnO_(4)^(-)` gains 5 mole electrons while in basic medium it gains 3 mole electrons.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are False.

Answer

To solve the question regarding the assertion and reason related to the equivalent weight of KMnO₄ in different media, we will follow these steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the equivalent weight of KMnO₄ in acidic medium is M/5 (where M is the molecular weight) and in basic medium, it is M/3.
- This means we need to verify if these values are correct based on the redox behavior of KMnO₄ in different media.

2. **Analyzing KMnO₄ in Acidic Medium**:
- In acidic medium, KMnO₄ is reduced from MnO₄⁻ (where manganese has an oxidation state of +7) to Mn²⁺ (where manganese has an oxidation state of +2).
- The change in oxidation state is calculated as follows:
\[ \text{Change in oxidation state} = +7 - (+2) = 5 \]
- Therefore, 1 mole of KMnO₄ gains 5 moles of electrons (5 electrons) in acidic medium.

3. **Calculating Equivalent Weight in Acidic Medium**:
- The equivalent weight (E) is given by the formula:
\[ E = \frac{M}{n} \]
where n is the number of electrons gained or lost.
- For acidic medium, n = 5, thus:
\[ E = \frac{M}{5} \]
- This confirms that the assertion regarding the equivalent weight in acidic medium is correct.

4. **Analyzing KMnO₄ in Basic Medium**:
- In basic medium, KMnO₄ is reduced to MnO₂ (where manganese has an oxidation state of +4).
- The change in oxidation state is calculated as follows:
\[ \text{Change in oxidation state} = +7 - (+4) = 3 \]
- Therefore, 1 mole of KMnO₄ gains 3 moles of electrons (3 electrons) in basic medium.

5. **Calculating Equivalent Weight in Basic Medium**:
- For basic medium, n = 3, thus:
\[ E = \frac{M}{3} \]
- This confirms that the assertion regarding the equivalent weight in basic medium is also correct.

6. **Understanding the Reason**:
- The reason states that in acidic medium, 1 mole of KMnO₄ gains 5 moles of electrons, and in basic medium, it gains 3 moles of electrons.
- Both statements are correct based on our calculations.

7. **Final Conclusion**:
- Both the assertion and reason are correct, and the reason correctly explains the assertion.

### Final Answer:
- Both the assertion and reason are true, and the reason is a correct explanation of the assertion.