If an iron rod is dipped into a solution of `CuSO_(4)` , the blue colour of the solution gradually fades away . Why ?

Explanation

Blue colour of a solution of `CuSO_(4)` is due to the presence of `Cu^(2+)` ions. Since `E_(Cu^(2+) |Cu)^(@)` is larger than `E_(Fe^(n+)|Fe)^(@),Cu^(2)` ions are reduced by Fe - rod , resulting in decrease in concentration of `Cu^(2+)` ions. This causes blue colour of the solution to fade away gradually .