Question

What is the oxidation state of $Cr$ in $Cr{O}_5$?

Answer 1

The oxidation state of $Cr$ is $+6$

Here there are 4 peroxide oxygen atoms with oxidation state -1 are present.

Only one oxygen(Double bonded O) is present with oxidation state -2.

Let oxidation state of the $Cr$ be $x$

Thus, oxidation state of the $Cr$ will be

$x+4(-1)+(-2)=0$

$x-6=0$

$\therefore x=+6$
Structure of $Cr{O}_5$