**Question:**

20ml of 0.2 M MnSO

_{4} are completely oxidised by 16ml ok KMnO

_{4} of unknown normality each forming Mn

^{+4} oxidation state. Find out the normality and molarity of KMnO

_{4} solution.

**My Attempt**I know that M

_{1}V

_{1}=M

_{2}V

_{2}.

So,

20*.2=M

_{2}*16

Solving this equation, i get:

M

_{2}=0.25M

I also know that Normality=Molarity * valency factor

So, Normality=0.25*4 (Due to the presence of Mn

^{+4} ion)

Hence, Normality of KMnO4 solution is 1.

But the answer given at the back is:

Normality = 0.5

Molarity = 0.167

Kindly Help...

Is there any mistake in my calculation?