Answer:
The iodine might have got into the bag by the process of diffusion/osmosis.
In the process of diffusion, particles move from an area of higher concentration to an area of lower concentration along a concentration gradient.
As we know, the iodine solution in the large container had more particles of iodine whereas the baggie had none of the iodine solution. As a result, a concentration gradient developed due to which iodine solution moved into the baggie through the process of diffusion or osmosis.