Which half reaction is most easily oxidized?

ag+ + e− → ag = 0.80 v

br2 + 2e− → 2br− = 1.07 v

fe3+ + e− → fe2+ = 0.77 v

zn2+ + 2e− → zn = –0.76 v

Explanation: All given reactions are the reduction half equations and given potentials are standard reduction potentials. Reduction takes place easily if the standard reduction potential is higher(positive) and oxidation takes place easily if the standard reduction potential is less(more negative).

Given standard reduction potentials for rest of the reactions are positive that makes them hard to oxidized and easy to reduced. Second equation is most easily reduced as its standard reduction potential is highest.

Looking at the given standard reduction potentials, the last equation is most easily oxidized as the standard reduction potential is least.

So, the correct choice is,

the answer is barium and copper bromide