Chlorine water is added to potassium iodide solution containing chloroform. The violet colour of the chloroform layer first deepens and then disappears when excess chlorine water is added, giving a colourless solution: $\mathrm{I}{}_2+5\mathrm{Cl}{}_2+6\mathrm{H}{}_2\mathrm{O}\to 2\mathrm{HIO}{}_3+10\mathrm{HCl}$. Which statements are correct? One or more options may be correct.

1. AThe colourless species contains iodine in the $+7$ oxidation state.
2. BExcess chlorine oxidises iodine to iodic acid, in which iodine is $+5$.
3. CTen electrons are lost per $\mathrm{I}{}_2$ molecule in the second step.
4. DThe violet layer is due to $\mathrm{I}{}_2$ dissolved in chloroform.