Calculate the standard cell potential for each of the electrochemical cells?

Question

What would the answers be to something like this? If someone could work out the answer I would really appreciate it. My online hw keeps telling me its wrong.

2Ag+(aq)+Pb(s)→2Ag(s)+Pb2+(aq)

E∘cell......V?

2ClO2(g)+2I−(aq)→2ClO−2(aq)+I2(s)

E∘cell......V?

O2(g)+4H+(aq)+2Zn(s)→2H2O(l)+2Zn2+(aq)

E∘cell......V?

Answer 1

See your other post above.