Equivalent weight of a substance varies with valency. Equivalent weight of potassium permanganate in acidic medium is ‘X’ and in neutral medium is ‘Y’ . X:Y is

Acidic medium:                               Mn+7O4-→Mn+2 ; Decrease in oxidation state per mole =5 EW (X) =M5 Neutral medium :                               Mn+7O4-→Mn+4O2 Decrease in oxidation state per mole =3 EW(Y) =M3∴ X : Y = 3 : 5