Question

why do the colour of CuSO4 changes when an iron nail is dipped in it???​

Answer 1

Answer:

When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour of the copper sulphate solution changes.

Answer 2

Answer:

The colour of copper sulphate solution (CuSO4) changes when an iron nail is dipped in it because iron(Fe) is more reactive than copper (Cu) and hence it displaces it.

Reaction

CuSO4 + Fe ==> FeSO4 + Cu

This is a Displacement Reaction.