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) to 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` due to the presence of two peroxide linkages, which can be calculated as In `CrO(O_(2))_(2)`, let the oxidation state of Cr be x.
`x+(-1) 4 + (-2) =0`
`x - 6 =0`
`x=+6`