An Antique Automobile Bumper Is to Be Chrome Plated

An antique automobile bumper is to be chrome plated. The bumper, which is dipped into an acidic Cr₂O₇^2- solution, serves as a cathode of an electrolytic cell. The atomic mass of Cr is 51.996; 1 faraday = 96,485 coulombs.
-If oxidation of H₂O occurs at the anode, how many moles of oxygen gas will evolve for every 3.30 × 10² g of Cr(s) deposited?

A) 8.46 mol
B) 9.52 mol
C) 4.23 mol
D) 6.35 mol
E) 3.17 mol