What groups of compounds gives a positive iodine test? what are some examples

What group of compounds gives positive test? Amylose Starch ( glucose)

Starch is a  large sugar molecules ( carbohydrate) that made out of amylose and amylopectine (doesn't participate in the reaction of iodine).

There are three groups of substances that are called carbohydrate. First group are monosaccharides that are simple sugar found in many fruits with a general formula of C6H12O6. The second group is disaccharides such as sucrose (table sugar) with a general formula of C12H22O11.  And finally the last group is called Polysaccharides such as starch and cellulose. So simple sugar found in apple juice, table sugar, starch and cellulose (wood, cotton) are all carbohydrates. Thus, If the material that is tested contains only cellulose or disaccharides, a positive result does not appear.

Positive iodine test occurs when amylose in starch reacts with iodine and results in turning the substance to blue-black or purple black colour.

An example of that would be potato, bread, cereal, wheat, corn and some other vegetables that store significant amount of starch. 

Hope that helps

thank u so much dear