Chlorine water is added dropwise, with shaking, to a solution of potassium iodide over a layer of chloroform, and then added in large excess. The chloroform layer is:

1. Aorange-brown at first, then pale yellow as a bromine compound forms
2. Bviolet at first, then colourless as $\mathrm{I}{}_2$ is oxidised to $\mathrm{HIO}{}_3$ (I: 0 to +5)
3. Cviolet, and it stays violet because chlorine cannot oxidise $\mathrm{I}{}_2$ further
4. Dcolourless throughout, because chloroform does not extract the product