Question 3
Why does copper deposit when zinc is added to aqueous copper sulphate solution, while zinc does not deposit when copper is added to zinc sulphate solution?
The right answer is the one marked above.
Because zinc is more reactive than copper. A metal can be displaced from a solution of its salt only by a metal more reactive than itself.
So zinc can displace copper but copper cannot displace zinc. The colour of the solution is not the reason — only the evidence that the reaction is happening.