Answer: it’s number 2 add a catalyst
Hopefully this helped :)
A reducing agent is one which is oxidised in the reaction itself. When you take into account the oxidation numbers you will see that the Cl- ions are oxidised from an oxidation number of -1 to 0 in Cl2. Therefore Cl- ions are the reducing agent.
Single replacement reactions. For example copper is more reactive than silver. So a copper wire in a silver solution will cause the silver to become a metal again.
