3. For the reaction between Cu and Sn the potentials are given below;

Cu2+(aq) +2e- -----------> Cu(s) Eºcathode = 0.34 (half-cell potential)
Sn(s) -----------> Sn2+(aq) + 2 e- Eºanode = - 0.14 (half-cell potential)

I don't see a question here.