Question

Why does the colour of copper sulphate solution change when an iron nail is dipped in it? ..

Answer 1

When an iron nail is placed in a copper sulphate solution, iron displaces copper from copper sulphate solution forming iron sulphate, which is green in colour.Therefore, the blue colour of copper sulphate solution fades and green colour appears.Heres the equation ..............
CuSO4  +Fe _____> FeSO4+Cu 

Hope this helps you ........!! Cheers @ thumps up :)

Answer 2

When an iron nail is dipped in copper sulphate solution , the displacement reaction takes place . The colour of copper sulphate solution fades due to the formation of light green solution of iron sulphate .