Answer:
In immunology, an antigen is a molecule or molecular structure, such as may be present on the outside of a pathogen, that can be bound by an antigen-specific antibody or B-cell antigen receptor. The presence of antigens in the body normally triggers an immune response.
I Am pretty sure the answer is cork
Answer: Under normal ambient conditions water is less dense as a solid than as a liquid, so ice floats on water. Most materials are more dense as solids.
Explanation: When water freezes, the molecules do not stack into a close-packed structure. They form a relatively open, honeycomb-like arrangement.
