To explain that iron is more reactive than copper, Take about 50ml of water in a beaker to which add 5gm of Copper sulphate in order to obtain copper sulphate solution which is blue in colour. Put a clean iron nail in this solution and keep the beaker for sometime undisturbed.

We will observe that the blue colour of copper sulphate solution starts fading gradually and the iron nail gets covered with a red-brown layer of copper metal. It is because iron is more reactive than copper, so it displaces copper metal from its solution of copper sulphate.

So, it is the copper metal that is free from its compound which forms a red-brown layer on the surface of iron nail. This shows that iron is more reactive than copper.