# solve 29.

Dear Student,
The change can be shown as

$C{r}_{2}{{O}_{7}}^{2-}\to C{r}^{3+}$
Cr changes from +6 to+3 hence there is a change of 3e​-
charge = $n×F$
so charge = 3F
we know 1F=96500
so charge needed = 289500 or 2.98$×{10}^{5}$C
hence correct option is (d)
Regards!

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