[buddhakhan]

1) WHY DO WE KEEP KMnO[4] IN DARK BOTTLE?
2) WHY KMnO[4] IS A SECONDARY STORAGE?
3) WHY H[2]SO[4] IS USED WHY NOT THE HCl AND HNO[3] IN REDOX TITRATION

[Albert]

A solution of potassium permanganate is not stable: it decomposes in the presence of light, acids, bases and it has to be stored at quite low temperature.
I think you can easily understand, reading between the lines, why it's not a primary standard, can't you?

Cl^- anions are oxidized to Cl₂; while nitric acid and permanganate compete as oxidizing agents.