LIFE SCIENCE

Detailed explanation-1: -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-2: -The extra hydrogen bonds that occur when water freezes increase the space between molecules, causing a decrease in overall density. In fact, each water ice molecule forms hydrogen bonds with four other molecules, while water molecules only form hydrogen bonds with an average of 3.4 other molecules.

Detailed explanation-3: -Point out that when water freezes, the water molecules have slowed down enough that their attractions arrange them into fixed positions. Water molecules freeze in a hexagonal pattern and the molecules are further apart than they were in liquid water. Note: The molecules in ice would be vibrating.

Detailed explanation-4: -On the other hand, when the temperature drops and water freezes, water molecules form a crystal structure maintained by hydrogen bonding (as there is too little heat energy left to break the hydrogen bonds). This structure makes ice less dense than liquid water.

Detailed explanation-5: -This is because as the temperature becomes colder, the water molecules lose energy and move less. The hydrogen bonds that form when water freezes into ice allow the molecules to be spaced farther apart, thus making them take more space, decreasing the overall density and making it float in the water.