how to determine decreasing ease of a reduction?

Question

for example, i know that Mg(s) reacts with Pb(NO3)2 (aq)---> Mg(NO3)2 (aq) + Pb (s) and thus:
Mg(s)-->Mg +2 (aq) [oxidized, reducing agent] and Pb +2 (aq) ---> Pb(s) [reduced, oxidizing agent]

so, with other redox reactions, like Zn (s) + Fe(NO3)2, how am i supposed to list the half rections in decreasing ease of reduction?

Answer 1

Look on any list of standard Oxidation/Reduction potentials for the elements.