Question

Why can't reach metal react to its own salt (example Copper and copper sulphate)?

Answer 1

To explain these I am taking one ex. consider
Fe+cuso4 the ans is feso4 and cu these reaction takes place bcz cuso4 will separat e into cu+. and so4- so. Fe is also + therefore it attack on so4-
now if both the ions are same there Will be two same charge so nothing will happened

Answer 2

each metal cannot react its Own salt because

the the reactive strength of the metal will be same in both example cu and cuso4.

In both the metal cu (copper) has the same reactive strenght. if in case there was fe (iron, more reactive than cu) to be reacted with cuso4 than displacement reaction would have taken place.

Hope it helps.