Explain the following :
Iodine is more soluble in KI solution than in water.

Explanation

In an aqueous solution of KI, `I_2` form a complex compound `KI_3`
`KI + I_2 rarr KI_3`
The compound ionises as follows in water
`KI_3 harr K^(+) + I_3^(-)`
Due to formation of the polyhalide `I_3^(-)` ion, `KI_3` dissolves in water. On the other hand, `I_2` being non-polar does not dissolve much in water.