Question

The oxidation number of $Cr\, in\, CrO_5$ is

• A. 3
• B. 5
• C. 6
• D. 0

Answer 1

Answer: (C)

6

Answer 2

In $CrO _{5}$, one oxygen is attached to $Cr$ through the double bond. It has oxidation number - 2. Four oxygen atoms are attached to Cr atom through a single bond. Each of these oxygen has an oxidation number $-1$. Let $x$ be the oxidation number of chromium. The sum of all the oxidation numbers is zero. Hence, $x-2+4(-1)=0$ and $x=6$ Thus, the oxidation number of chromium in $CrO _{5}$ is $+6$.