Question

why dose the colour of copper sulphate change when an iron-nail is dipped in it?​

Answer 1

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.

Answer 2

Explanation:

when iron nail is dipped in copper sulphate solution iron being more reactive displaces copper from its solution .. reactants : copper sulphate and iron ... products : iron sulphate and copper ... the solution changes from blue to pale green

CuSO4 + Fe gives FeSO4 + Cu