I am a college student majoring in Psychology and minoring in Philosophy. I write critically with zero error. I have confidence in my ability to grasp the central idea or message being transmitted by an article, and thus know how to do that myself while writing one.
The molecules of water, upon the drop in temperature, lose energy. Their ability to move is lessened. At freezing level, when water is ice, its molecules are stable. And ice has less density than that of water, thus it doesn't sink, and remains afloat.