Chemistry - Redox Reactions Question with Solution | TestHub

I is correct: in acid, $\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7^{2-}$ $\to$ $2C{\mathrm{r}}^{3+}$ gains 6 ${\mathrm{e}}^{-}$ per formula unit ($n$ = 6), while in strong base $\mathrm{Mn}{\mathrm{O}}_4^{-}$ $\to$ $\mathrm{Mn}{\mathrm{O}}_4^{2-}$ gains only 1 ${\mathrm{e}}^{-}$ ($n$ = 1), so one mole carries 6 and 1 g-eq respectively. II is also correct as a statement about chromium's reduction. But II only accounts for the dichromate half of I; it says nothing about permanganate in base, so it is not the complete explanation of I. Hence (b).