A solution of iodine and potassium iodide is dripped on to a substance and if it contains starch, a deep blue colour will materialise. Here's the science bit! Starches contain a sugar called ...

Organic solvents with densities greater than and less than that of the aqueous solution are used to extract the iodine. The aqueous solution of food color is blue. Iodine in water is yellow, and when ...