Some experiments were carried out to place the metals copper, nickel and silver in reactivity series order. Experiment 1: a piece of copper was placed in some green nickel(II) sulfate solution. There was no change to either the copper or the solution. Experiment 2: a coil of copper wire was suspended in some silver nitrate solution. A furry grey growth appeared on the copper wire, out of which grew spiky silvery crystals. The solution gradually turned from colourless to blue. a) Use this information to place copper, nickel and silver in reactivity series order, starting with the most reactive one. b) In another experiment, a piece of nickel was placed in some copper(II) sulfate solution. (i) Write down any one change that you would observe during this reaction. (ii) Write the full balanced equation for this reaction. (Assume that nickel(II) sulfate solution is formed.) (iii)Write the ionic equation for this reaction, and use it to explain which substance has been oxidised during the reaction.