An iron nail was immersed in a solution of copper sulfate and when it was removed from the solution, it was coated with a layer of copper metal. Hereafter, a different iron nail was immersed in a solution of zinc nitrate and removed this nail rusted?(con)

Reactive metals displace unreactive metal ions from their solutions.

Iron in the first nail was capable of reducing and displacing copper ions in the #"Cu" "SO"_4# solution indicating that #"Fe"# is more reactive than #"Cu"#.

#ul("Fe" (s)) + "CuSO"_4 to ul("Cu"(s)) + "FeSO"_4(aq)#

What's going on with the second nail might not be as evident as the first one. Let's start with an assumption: assuming that iron #"Fe"# is more reactive than zinc such that it is capable of replacing zinc #"Zn"# from its solution.

Immersing the iron nail in the #"Zn"("NO"_3)_2# solution will coat it with a layer of metallic zinc. Coating iron, a metal that rusts- or gets oxidized- rapidly in humid air, with a layer of less reactive metal would hinder its oxidation. By this assumption, coating zinc would make the iron nail not as suspectable to rusting as a nail with no coating. However, the observation that the two nails rust at the same rate disagrees with the assumption meaning that iron is less reactive than zinc. Thus

#"Zn">"Fe"#

Also,

#"Fe">"Cu"#

therefore

#"Zn">"Fe">"Cu"#