When water freezes, it expands in volume by about

This question tests knowledge of the unique physical properties of water. Unlike most substances, water exhibits anomalous expansion when it freezes. When water turns into ice, its volume increases by approximately 9%. This occurs because the hydrogen bonds in liquid water form a more open, crystalline lattice structure in ice, holding the molecules further apart. This property is crucial for life on Earth, as it causes ice to float, insulating aquatic environments and preventing entire bodies of water from freezing solid.

• 3%, 6%, and 10% are incorrect percentages. The widely accepted and scientifically accurate value for water's expansion upon freezing is around 9%.