Pyrolusite is fused with KOH and KNO3 to give a green compound X. X on acidification (or by passing CO2) gives a purple compound Y and a brown precipitate Z. Using K = 39, Mn = 55, O = 16, the equivalent mass of Y as an oxidant in acidic medium is

JEE Advanced levelSingle correct optionDifficulty 3 of 3df101

Pyrolusite is fused with KOH and $KNO X_{3}$ to give a green compound X. X on acidification (or by passing $CO X_{2}$ ) gives a purple compound Y and a brown precipitate Z. Using $K = 39$ , $Mn = 55$ , $O = 16$ , the equivalent mass of Y as an oxidant in acidic medium is

X is

K X_{2} MnO X_{4}

, Y is

KMnO X_{4}

(molar mass

39 + 55 + 64 = 158

) and Z is

MnO X_{2}

. In acidic medium

MnO X_{4} X^{-}

gains 5 electrons (

+ 7 \to + 2

), so equivalent mass

= 158/5 = 31.6

. The values

52.7

and

158

belong to neutral and strongly alkaline media.