Question

what happens if you mix Cu + Al(NO3)3

Answer 1

I don't think that there will be any reaction as Copper (Cu) is less reactive than Aluminium (Al) . Hence, Copper (Cu) will not be able to displace Al from Al(NO3)3

Therefore :
\(\mathsf{Cu + Al{(NO_3)}_3 \rightarrow \text{No Reaction}}\)