Iodine dissolves more in `KI` solution than in water. Why?
(b) Colour of `KI` solution containing starch turns deep blue when chlorine water is added. Explain.

Explanation

(a) Iodine , `I_(2)` is a convalent molecule. Hence it is less soluble in polar solvent i.e. water `H_(2)O`. In `KI` solution, `KI` reacts with water to form `KI_(3)` which is an ionic compound, `K^(o+)I_(3)^(Ө)`. Being ionic, `Kl_(3)` is more soluble in water.

(b) Chlorine being a strong oxidising agent displaces iodine from `Kl` i.e. oxidises `I^(Ө)` to `I_(2)`. Iodine is absorbed by starch and thus deep blue coloured solution is obtained due to formation formed of strach `-I_(2)` adsorption complex.
`2Kl+Cl_(2) rarr 2KCl+I_(2)`
`I_(2)+Starch rarr [Starch-I_(2)]` absorption complex.