Question

life as we know it could not exist without water. All the chemical reactions of life occur in an aqueous solution. Water molecules are polar and are capable of forming hydrogen bonds with other polar or charged molecules. As a result, water has the following properties:
A. H2O molecules are cohesive; they form hydrogen bonds with each other.
B. H2O molecules are adhesive; they form hydrogen bonds with polar surfaces.
C. Water is a liquid at normal physiological (or body) temperatures.
D. Water has a high specific heat.
E. Water has a high heat of vaporization (energy needed to evaporate)
F. Water's greatest density occurs at 4°C

Answer 1

a) At 0 C water forms ice but as mentioned above F) water's greatest density occurs at 4 C and it decreases below 4 C so ice is lighter than 4C water, thus, at 0C ice comes to surface and acts as insulator thereby preventing lower water from freezing.