Question

Iron nails were dipped in a beaker containing a blue solution. After some time, it was observed that the colour of the solution changed from blue to green. Which of the following reactions correspond to the recorded observations?

• A. Zn + CuSO${}_4$ → Cu + ZnSO${}_4$
• B. Fe + CuSO${}_4$ → Cu + FeSO${}_4$
• C. Fe + ZnSO${}_4$ → Zn + FeSO${}_4$
• D. Zn + FeSO${}_4$ → Fe + ZnSO${}_4$

Answer 1

The correct option is B Fe + CuSO${}_4$ → Cu + FeSO${}_4$

The given blue colour solution is copper sulphate (CuSO${}_4$) solution in which iron (Fe) nails are dipped.
Iron is more reactive than copper and, hence, shows a displacement reaction. Iron displaces copper from the copper sulphate to produce ferrous sulphate solution, which is green in colour.
The reaction can be shown as follows:
Fe + CuSO${}_4$ → Cu + FeSO${}_4$