Question

an iron knife kept dipped in a blue copper sulphate solution turns the blue solution light green.why

Answer 1

Iron from the knife displaces the copper from copper sulphate solution (copper being less reactive than iron).

Answer 2

Iron is more reactive than copper. So, it displaces Cu from CuSO4 solution and forms light green ferrous sulphate.

CuSO4 + Fe ----> FeSO4 + Cu

Blue colour Light green colour