Question

x +yso4=xso4+y----------no reaction of the elements 'X'and Y which is more reactive and why

Answer 1

x is more reactive than y

Answer 2

y will be more reactive as x can't displace it n according to reactivity series elements which have lower reactivity can't displace element who have higher reactivity...
ex. Cu + ZnSO4 --- no reaction
as cu is less reactive than Zn
hope it helps ...