ACT Science Exam Prep

Answer: D - The density of water as a solid is lower than its density as a liquid. Unlike most substances, solid water (ice) is less dense than liquid water.

Key Takeaway: Water has numerous essential properties that are important biologically and in other aspects of life. Its high surface tension allows large entities such as boats to flow instead of sink. It is known as the “universal solvent” since virtually any substance can be dissolved into water. Unlike most substances, water is denser as a liquid than as a solid. Water is the only naturally occurring substance that exists in all three states of matter, water vapor, liquid water, and ice.