(i) Colour of the solution in the beaker changes from blue to green.
(ii) A brown coloured deposit is found on the surface of the iron nail.
(b) These changes are chemical changes as the new substances are formed in the form of iron sulphate and copper.
Copper sulphate(blue) + Iron → Iron sulphate(Green) + copper
When an iron nail immersed in the solution of copper sulphate than iron displaces copper from the solution of copper sulphate because iron is more reactive than copper. Therefore copper sulphate solution colour changes from blue to pale green.
When an iron nail is dipped in copper sulphate solution, a brown coating of copper is formed in the surface of iron and the colour of copper sulphate solution changes from blue to pale green. The reaction shows that iron is more reactive than copper because it displaces copper from the copper sulphate solution. The iron passes into the solution as Fe (II) forming the ferrous sulphate solution.