<span>I think its made of food oxidation.</span>
Answer:
Diffusion.
Explanation:
According to the information given before the example in the question and considering the fact that the bag was secured on both ends before being placed in the solution, provided that there were no holes on the surface of the bag, the iodine solution could have diffused through the bag into the starch solution hence the color change to black after 30 minutes.
I hope this answer helps.
