Question

Which one of the following reactions does not involve either oxidation or reduction

• A. $V{O}_2^{+}\to V_2{O}_3$
• B. $Na\to N{a}^{+}$
• C. $Cr{O}_4^{2-}\to C{r}_2{O}_7^{2-}$
• D. $Z{n}^{2+}\to Zn$

Answer 1

The correct option is C $Cr{O}_4^{2-}\to C{r}_2{O}_7^{2-}$

$\begin{array}{cc}\dot{Cr{O}_4^{2-}}& \dot{Cr{O}_2{O}_7^{2-}}\\ x+\left[\right(-2)\times 4=-2]& 2x+(-2)\times 7=-2\\ x=8-2=6& 2x=14-2=12\\ & x=\frac{12}{2}=+6\end{array}$

In this reaction oxidation and reduction are not involved because there is no change in oxidation number