100 mL solution of ferric alum `[Fe_(2)(SO_(4))_(3).(NH_(4))_(2)SO_(4).24H_(2)O`
`(Mw=964g mol^(-1))` containing `2.41 g ` salt was boiled with Fe when the reaction
`Fe+Fe_(2)(SO_(4))_(3)to3FeSO_(4)`
Takes place. The unreacted iron was filtered off and the solution was titrated with `(M)/(60)K_(2)Cr_(2)O_(7)` in acidic medium.
Q. What is the titre value of `K_(2)Cr_(2)O_(7)` when Fe reacts with `Fe_(2)(SO_(4))_(3)`?

Options

A. 25 mL
B. 50 mL
C. 75 mL
D. 100 mL

Answer

C

Explanation

`m" Eq of "FeSO_(4)-=m" Eq of "K_(2)Cr_(2)O_(7)`
`((3xx2.41)/(964))xx10^(3)-=(1)/(60)xx6` (n factor) `xxV(mL)`
`V=75mL`
`(Fe^(2+)toFe^(3+)+e^(-))(6e^(-)+Cr_(2)O_(7)^(2-)to2Cr^(3+))`