Answer:
Pb(s)------>Pb2+(aq)
Explanation:
If you look at the oxidation numbers Pb increases from 0 to +2 while Cu decreases from +2 to 0.Hence,Pb is the reducing agent and Cu2+ is the oxidizing agent.
Also, a thing to note is that the oxidation number of any solid is always 0.
~Hope this helps:)
