A platinum cathode is used to electrolyze a CuSO₄(aq) solution with a constant current of 0.800 A for 40.0 min. The total charge that flows is 1.92 × 10³ C, but only 0.340 g of Cu is plated. What percentage of the electric charge is diverted to a competing reaction rather than to copper deposition? (Atomic mass: Cu = 63.5 g mol⁻¹; Faraday constant = 9.65 × 10⁴ C mol⁻¹)
(a) 54%
(b) 73%
(c) 46%
(d) 79%