Question

why do displacement reaction takes place if both the products in the reaction are stable

Answer 1

Displacement reaction takes place when one element is more reactive than other element as per the reactivity series..One more necessary condition for displacement is if both the products so formed are stable.
ex:- Fe+CuSO4 -> FeSO4 +Cu..

Here Iron displaces Copper metal from its aqueous soln. to form Iron Sulphate ..