Question

Oxidation number of $Cr$ in $Cr_{2} O^{2-}_{7}$ is

• A. $+2$
• B. $+4$
• C. $+6$
• D. $+7$

Answer 1

Answer: (C)

$+6$

Answer 2

Let the oxidation number of $Cr$ in $Cr_{2}O^{2-}_{7}$ is $x$. $2x + \left(7 \times -2 \right) = -2$ $2x = - 2 + 14$ or $x - 12/2 = + 6$