Answer:
Potassium iodide
Step-by-step explanation:
The white solid introduced into the solution is potassium bromide. This is an ionic solid thus it quickly dissolves in water to yield a colorless solution.
When chlorine is added to this solution, the iodine is displaced since chlorine is above iodine in the electrochemical series.
When mixed with hexane, the color of the solution changes to purple.