Question

What is the magnitude of summation of oxidation states of all oxygen in $Cr{O}_5$?

Answer 1

The IUPAC name of $Cr{O}_5$ is chromium (VI) peroxide or chromium (VI) oxide peroxide or monochromium (VI) pentaoxide.

As shown in the structure, one oxygen atom has an oxidation state of $-2$ and four other oxygen atoms (that are a part of two peroxide linkages) have an oxidation state of $-1$ each.

The summation of oxidation states of all oxygen atoms in $Cr{O}_5$ is as follows:

$1(-2)+4(-1)=-6$

Hence, the magnitude of summation of all oxidation states in $Cr{O}_5$ is $6$.