Question

when a metal X is added to salt solution of a metal Y following reaction takes place : 1) metal X +salt solutions of Y -> salt solution of X +metal Y 2)mention the inference you draw regarding the reactivity of metal X and Y and also the reason of your conclusion.

Answer 1

x must be lying above Y in the reactivity series so it displaces Y from it's salt...
it can be seen by taking an example as:-
Al2(SO4)3+2Mg----> 2MgSO4 +3Al

Answer 2

Metal X should be taken as a highly reactive metal than Metal Y

               For example:

                                  Fe+ CuSO4-------->FeSO4 +Cu

                                    Here Fe is more reactive than Cu