The correct option is A 0.34V
The given electrode potentials are:
Cu2++e−⇌Cu+, E01=+0.18V;ΔG01=−1×0.18×F unit
Cu++e−⇌Cu, E02=0.50V,ΔG02=−1×0.50×F unit
Let the required electrode potential be x V. Then
Cu2++2e−⇌Cu, E0=x0; ΔG0=−2×x×F unit
Now for the electrode reaction
ΔG0=ΔG01+ΔG02
⇒(−2×x×F)=(−0.18F)+(−0.50F), x=0.34V