Question

When iron rod is Kept dipped in copper sulphate solution for some time, a brown coating is formed on the iron rod why? What change will observe with the colour of solution

Answer 1

iron is more reactive than copper..so it displaces copper from its sulphate solution and ferrous sulphate solution is formed...The colour of solution was earlier blue...but now the colour of the solution fades and it becomes very light blue...
CuSO4+Fe = FeSO4+Cu

Answer 2

This all happens because iron when dipped in CuSO4, Iron being more reactive than copper, displaces copperfrom the solution.
So copper gets deposited on the surface of the rod. The colour of the solution will change from blue to fade green.
Hope this helps