Question

colour of copper sulphate solution change when an iron nail is dipped<br /> in it

Answer 1

So, when an iron nail is dipped in a copper sulphate solution, iron displaces copper from its solution to form iron sulphate, which is green in color. Hence, the blue color of copper sulphate solution changes into green color because of this displacement reaction

Answer 2

metals r arranged in a series called metal reactive series
when an iron nail is dipped in sulphate solution the colour of the copper sulphate solution changes from blue to Green this is because high reactive metals displace less reactive metal