Why is ice less dense than water?
A) When water freezes, the molecules arrange into a crystal form in which they are farther apart than in liquid water.
B) As a solid, ice is actually denser than water, but will still float due to the high surface tension of water.
C) Water molecules lose one of their hydrogen atoms when they form ice, making the solid form less dense than the liquid form.
D) As water freezes, it forms cubic crystals made only of eight atoms. These atoms weigh less in ice than in water.

Question

Quizplus · Accepted Answer

When water freezes, its molecules arrange into a hexagonal crystal structure that causes them to be spaced further apart than in liquid form, making ice less dense than water. This is why ice floats on water.

Why Is Ice Less Dense Than Water