Question

ice cubes float in a glass of water because:
the ice is losing mass through the melting process.
the molecules of ice are arranged in such a way to leave empty space.
liquid water is less dense than ice cubes.
the colder ice is more dense.

Explanation:

Ice has a hexagonal crystalline molecular structure that creates empty spaces, making its density ($0.917 \, \text{g/cm}^3$) lower than liquid water ($1.0 \, \text{g/cm}^3$). Objects less dense than the fluid they are in float, which is why ice cubes float in water. The other options are incorrect: melting does not reduce mass, liquid water is denser than ice, and colder ice is not more dense than liquid water.

Answer:

The molecules of ice are arranged in such a way to leave empty space.