Answer:
+ 1.20 V.
Step-by-step explanation:
The standard sell potential E°cell = E°cathode - E°anode.
- The cathode is the one with the more positive E° (E°Ag⁺), while the anode is the one with the less positive value E⁰ (E⁰Cu²⁺).
∵ E°cell = E°cathode - E°anode = E°Ag⁺ - E⁰Cu²⁺ = + 0.80 V - (- 0.40 V) = + 1.20 V.