AP BIOLOGY

Detailed explanation-1: -Because it is less dense, ice floats on the surface of liquid water, as we see for an iceberg or the ice cubes in a glass of iced tea. In lakes and ponds, a layer of ice forms on top of the liquid water, creating an insulating barrier that protects the animals and plant life in the pond below from freezing.

Detailed explanation-2: -The solid states of other liquids are denser because the molecules pack together tightly when the kinetic energy (temperature) decreases. The hydrogen bonds in water ice are indeed strong, but their orientation causes molecules to push apart, actually lowering density.

Detailed explanation-3: -When water freezes, water molecules form a crystalline structure maintained by hydrogen bonding. Solid water, or ice, is less dense than liquid water. Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density.

Detailed explanation-4: -This ice layer insulates the water below it, allowing it to stay liquid, which allows the life within it to survive. If ice sank, the liquid water on top would also freeze and sink, until all the liquid water became frozen. Water is less dense as a solid, than as a liquid, which is why ice floats.

Detailed explanation-5: -Water is less dense as a solid than as a liquid. This property is important, as it keeps ponds, lakes, and oceans from freezing solid and allows life to continue to thrive under the icy surface.