Why does ice float on liquid water?

Why does ice float on liquid water?

• A. Ice is denser than water
• B. Water expands when heated
• C. Ice dissolves in water
• D. Ice has a crystalline open lattice making it less dense

Answer: (D)

Buoyancy depends on density. Ice floats because it is less dense than liquid water. In solid water, hydrogen bonds hold molecules in a crystal lattice that spaces them further apart, creating an open structure. This arrangement lowers the density of ice (about 0.92 g/cm³) compared with liquid water (about 1.00 g/cm³), so the ice cube experiences a greater upward buoyant force than its weight and rises. The other ideas don’t explain flotation as directly: saying ice is denser would mean it sinks, and says water expands when heated is about heating, not freezing, and doesn’t address why a solid would float. Dissolving in water isn’t relevant to buoyancy either.

Buoyancy depends on density. Ice floats because it is less dense than liquid water. In solid water, hydrogen bonds hold molecules in a crystal lattice that spaces them further apart, creating an open structure. This arrangement lowers the density of ice (about 0.92 g/cm³) compared with liquid water (about 1.00 g/cm³), so the ice cube experiences a greater upward buoyant force than its weight and rises.

The other ideas don’t explain flotation as directly: saying ice is denser would mean it sinks, and says water expands when heated is about heating, not freezing, and doesn’t address why a solid would float. Dissolving in water isn’t relevant to buoyancy either.