Chromium plating of an article was carried out. If during electrolysis, the weight of the article increased by 2.6 g and 0.56 dm³ of oxygen (at STP) evolved at the inert anode, the oxidation state of the chromium ions being discharged must be:
Correct answer: C. +3
- A. +1
- B. +2
- C. +3
- D. +6
Explanation
0.56 dm³ of O₂ at STP is 0.025 moles O₂ evolution at the anode shows 0.1 mol e⁻ passed.0.05 mol Cr deposited at cathode → 0.1 / 0.05 = 2 electrons per Cr atom. n-factor = 2 → initial oxidation state of Cr = +3.
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