In acidic medium, `H_(2)O_(2)` changes `Cr_(2)O_(7)^(2-)` to `CrO_(5)` which has two `(-O-O-)` bonds. Oxidation state of Cr in `CrO_(5)` is

Options

A. `+5`
B. `+3`
C. `+6`
D. `-10`

Answer

C

Explanation

When `H_(2)O_(2)` is added to an acidified solution of a dichromate, `Cr_(2)O_(7)^(2-)`, a deep blue coloured complex, chromic peroxide, `CrO_(5)`[or `CrO(O_(2))_(2)`] is formed.
`Cr_(2)O_(7)^(2-)+2H^(+)+4H_(2)O_(2) rarr underset(Chromic peroxide)(2CrO(O_(2))_(2)+5H_(2)O)`
This deep blue coloured complex has the following structure

Oxidation state of `Cr` is `+6` is due to the presence of two peroxide linkages, which can be calculate as
`Cr` peroxide normal
`x+(-1)4+(-2)=0`
`x-6=0`
`x=+6`