Across nine experiments designed to test the reactivity of the halogens, an aqueous solution of each halogen is mixed with the same volume of an aqueous solution containing halide ions, as shown in the table. Each of the nine mixtures is then shaken separately with the same volume of hexane. The nine tubes are left until the aqueous and organic solvents form separate layers. How many test-tubes have a purple top hexane layer?
- A1
- B2
- C3
- D5