question_answer 6)

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

Answer:

The reaction between copper(II) sulphate and iron is represented as                                                                                                                                                                                                     In this displacement reaction, a more active element iron displaces another less reactive element from its compound copper(II) sulphate. The brown copper metal gets deposited on the iron nails. The colour of the solution changes from blue to light green due to the formation of  ions.