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Assertion (A): When KMnO4 acts as an oxidising agent in alkaline medium, its equivalent mass equals one-third of its molecular mass. Reason (R): The oxidation number of Mn in KMnO4 is +7. Choose the correct option.
- Both (A) and (R) are true and (R) is the correct explanation of (A)
- Both (A) and (R) are true but (R) is not the correct explanation of (A)
- (A) is true but (R) is false
- (A) is false and (R) is true
Correct answer: Both (A) and (R) are true but (R) is not the correct explanation of (A)
Solution
In alkaline medium Mn changes +7 to +4 (3 electrons), so equivalent mass = M/3 (A true); R correctly states the +7 state but that alone does not explain the factor of 3, which comes from the 3-electron change.
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