Question: what is the chemical reaction between iodine and starch?
Answer: Starch is a polysaccharide consisting of two kind of molecules : amylose and amylopectin. Amylose in starch is responsible for the formation of a deep blue color in the presence of iodine. In the Iodine test , Iodine dissolved in aqueous solution of Potassium Iodide (KI) reacts with starch producing a bluish colour.