An iron nail was dropped into copper sulphate solution. After some time, the colour of the solution changed from :
light green to blue
blue to light green
light green to colourless
blue to yellow

Correct answer: (2)Blue to light green

Explanation: The iron nail gets covered with a red-brown coating of copper metal and the blue colour of copper sulphate solution changes to greenish as iron nail displaces copper from copper sulphate solution to form ferrous sulphate.