AP BIOLOGY

Detailed explanation-1: -Water is unique, however, because its solid state (ice) is actually less dense than its liquid phase, allowing walleye and other aquatic life the ability to survive underneath the ice in cold, but unfrozen waters each winter.

Detailed explanation-2: -In ice crystals, their hydrogen bonds link them together like acrobats, stacked one on top of the other, with their arms and legs outstretched. This provides more space between the molecules in the crystal structure of ice than the molecules of liquid water. As a result, ice is less dense than the liquid form.

Detailed explanation-3: -Macroscopically, water at ordinary temperatures is a clear, nearly colorless liquid. Its density is 0.98 g cm–3 at room temperature, as compared with only 0.92 g cm–3 for ice, a fact that must be explained by atomic/molecular theory.

Detailed explanation-4: -Ice is less denser than water because in ice, the molecules arrange themselves in a rigid tetrahedral structure due to which cage like spaces remain in their bonding but water molecules remain in linear bonding form. As the volume of ice becomes greater, it is less denser.