5. Classification & Balancing of Chemical Reactions

Which element is the best reducing agent?

Determine whether which of the following redox reactions will occur spontaneously in the forward direction?

a) Ni(s) + Zn²⁺(aq) → Ni²⁺(aq) + Zn(s)
b) Fe(s) + Pb⁴⁺(aq) →   Fe²⁺(aq) + Pb(s)
c) Al(s) + Ag⁺(aq) →  Al³⁺(aq) + Ag(s)
d) Pb(s) + Mn²⁺ (aq) → Pb²⁺(aq) + Mn(s)

Suppose you wanted to cause Ni²⁺ ions to come out of solution as solid Ni. Which metal could you use to accomplish this?