GEOLOGY

Detailed explanation-1: -When water freezes, however, it expands, becoming less dense. If equal volumes of cold water (down to 4deg. C, 39.2deg. F) and hot water are compared, cold water weighs more than hot water.

Detailed explanation-2: -Because there’s more space between the molecules, a volume of hot water has fewer molecules in it and weighs a little bit less than the same volume of cold water. So hot water is less dense than cold water.

Detailed explanation-3: -Since cold water is more dense, it sinks in the room temperature water. When water is heated, the water molecules move faster and spread out more. This makes hot water less dense than room temperature water. Since hot water is less dense, it floats on the room temperature water.

Detailed explanation-4: -Cold water has a higher density than warm water. Water gets colder with depth because cold, salty ocean water sinks to the bottom of the ocean basins below the less dense warmer water near the surface.

Detailed explanation-5: -Cold water weighs about 8.33 lbs/ gal; hot water about 8.3. So yeah cold water is heavier, but not by much.