Equal amounts of the same reductant are titrated with KMnO4 under three conditions: acidic (to Mn^2+), neutral (to MnO2) and strongly basic (to MnO4^2-). Let the moles of KMnO4 consumed be x_a, x_n and x_b respectively. Which statements are correct?

The equivalent mass of KMnO4 in strongly basic medium equals its molar mass M.

The equivalent mass of KMnO4 in neutral medium is M/5.

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3eq202

Equal amounts of the same reductant are titrated with $KMnO X_{4}$ under three conditions: acidic (to $Mn X^{2 +}$ ), neutral (to $MnO X_{2}$ ) and strongly basic (to $MnO X_{4} X^{2 -}$ ). Let the moles of $KMnO X_{4}$ consumed be $x_{a}$ , $x_{n}$ and $x_{b}$ respectively. Which statements are correct?

A $x_{n} = \frac{5}{3} x_{a}$
BThe equivalent mass of $KMnO X_{4}$ in strongly basic medium equals its molar mass $M$ .
C $x_{b} = 5 x_{a}$
DThe equivalent mass of $KMnO X_{4}$ in neutral medium is $M /5$ .

The n-factors are 5 (acidic), 3 (neutral) and 1 (basic). For a fixed number of equivalents of reductant, moles of

KMnO X_{4}

vary as

1/ n

x_{a} : x_{n} : x_{b} = 1/5 : 1/3 : 1 = 1 : 5/3 : 5

. Equivalent mass in neutral medium is

M /3

, not

M /5

, and in basic medium it is

M /1 = M