Correct Answer: blue, green

Solution : The correct option is blue, green .

When an iron nail is dipped into a coloured copper sulphate (copper (II) sulphate) solution, the colour change observed is typically from blue to green. This is because the iron in the nail reacts with the copper sulphate solution, displacing copper ions and forming iron sulphate while causing the solution to change colour. The original blue colour of the copper sulphate solution turns green due to the formation of iron sulphate and the release of copper ions into the solution.