Ncert Exercises & Solutions

Given below are two statements:

Assertion (A):	In the reaction between potassium permanganate and potassium iodide, permanganate ions act as an oxidising agent.
Reason (R):	The oxidation state of manganese changes from +2 to +7 during the reaction.

1.	Both (A) and (R) are true and (R) is the correct explanation of (A).
2.	Both (A) and (R) are true but (R) is not the correct explanation of (A).
3.	(A) is true but (R) is false.
4.	(A) is false but (R) is true.

Hint: Mn oxidation state in KMnO₄ is +7.

The reaction is as follows:

10 KI + 2 K \overset{+ 7}{M} {nO}_{4} + 8 H_{2} {SO}_{4} \to 2 \overset{+ 2}{M} {nSO}_{4} + 6 K_{2} {SO}_{4} + 8 H_{2} O + 5 I_{2}

The oxidation state of Mn decreases from +7 to +2.

Hence, the Assertion is true but the reason is false.