Question

Oxidation number of $Cr$ in $Cr{O}_{2}C{l}_2$ is $+6$. Oxidation number (per atom) of oxygen is:

• A. $-2$
• B. $+2$
• C. $-1$
• D. $+1$

Answer 1

The correct option is A $-2$

Let the oxidation state of $O$ be $x$.

Since, the compound $Cr{O}_{2}C{l}_2$ is neutral, sum of oxidaton states of all elements must be zero.
Hence, $6+2x-2=0$ (neutral compound)
So, $x=-2$
Hence, the oxidation state of $O$ is $-2$.