Answer 1

When a piece of iron is placed in copper sulphate solution, it becomes brown in colour and the blue colour of the copper sulphate solution fades. This is because iron, being more reactive metal than copper, displaces copper from its solution.
       Fe (s) + CuSO₄ (aq) → FeSO₄(aq) + Cu(s)
Thus, the type of reaction involved is displacement reaction