Chromium plating can involve the electrolysis of an electrolyte of an acidified mixture of chromic acid and chromium sulphate. If during electrolysis the article being plated increases in mass by `2.6g` and `0.6dm^(3)` of oxygen are evolved at an inert anode, the oxidation state of chromium ions being discharged must be `: (` assuming atomic weight of `Cr=52` and `1 mol e` of gas at room temperature and pressure occupies a volume at `24dm^(3))`

Options

A. `-1`
B. Zero
C. `+1`
D. `+2`

Answer

c

Explanation

`4H^(o+) rarr O_(2)+2H_(2)O+4e^(-)implies1 mol-=4F`
`implies(0.6)/(24) mol -=4xx(0.6)/(24)=0.1F`
`Cr^(3+)+xe^(-) rarr Cr^((3-x)o+)`
`implies1mol--=xFimplies(2.6)/(52)mol-=(x)/(20)F-=0.1Fimpliesf=x=2`
`implies` Oxidation state of `Cr^((3-2))=Cr^(+1)=+1`.