Florida Biology EOC Practice Test

When water freezes and expands, what effect does this have on its density?

1. Freezing makes water more dense

2. Freezing makes water less dense

3. Freezing does not change density

4. Freezing only affects density in saltwater

The correct answer is: Freezing makes water less dense

When water freezes and expands, it forms a crystalline structure that takes up more space than liquid water. This expansion causes the density of ice to be less than the density of liquid water. Therefore, when water freezes, it becomes less dense, making option B the correct answer. Option A is incorrect because freezing water actually makes it less dense, not more dense. Option C is incorrect because freezing does change the density of water. Option D is incorrect because the density of water changes when it freezes regardless of whether it is freshwater or saltwater.