MCQ
In $K _2 Cr _2 O _7$ titration, using the indicator diphenylamine, an intense blue color is obtained just after the equivalence point. In this process, $Cr _2 O _7^{2-}$ oxidizes the indicator and itself undergoes reduction. How many electrons are needed when the following half-reaction is balanced?
$Cr_2 O_7^{2-}+H^{+}+? e^{-} \longrightarrow Cr^{3+}+H_2 O$
$Cr_2 O_7^{2-}+H^{+}+? e^{-} \longrightarrow Cr^{3+}+H_2 O$
- A4
- B2
- ✓6
- D3