Which pair of reactants will not react?

Question

Au(s) with Hg^2+ (aq)
Pt^2+ (aq) with Au(s)
Ag(s) with Cu(s)

Au(s) -> Au^3+(aq) + 3e-
Hg(s) -> Hg^2+(aq) + e-
Pt(s) -> Pt^2+(aq) + 2e-
Cu(s) -> Cu^2+(aq) + 2e-

My guess is all of them, but I am not entirely sure.

Answer 1

Here is an activity series table. Use it to answer the question.
http://www.grandinetti.org/activity-series

Here is how you do it.
Any METAL will displace (react with) any METAL ION below it in the activity series. For example,
Sn will react with Cu^2+ ion.
Sn + CuCl2 ==> SnCl2 + Cu because the free element Sn is above Cu in the activity series but
Cu + SnCl2 ==> no reaction because Cu is BELOW Sn in the activity series.