Question

The number of moles of electron required to reduce $0.2$ mole of $C{r}_2{O}_7^{-2}$ to $C{r}^{+3}$

• A. 12
• B. 0.6
• C. 1.2
• D. 6

Answer 1

Answer: (C)

$C{r}_2^{+6}{O}_7^{2-}\to [6e^{-}]2C{r}^{+3}$
$1$ mol requires 6 mole of electrons
$0.2$ mol requires $\frac{0.2\times 6}{1}=1.2$ mol of electrons