>>11070813Because ice is less dense than water. H2O is the only known substance whose solid form is actually less dense than its liquid form. This is because water can form the most ammount of hydrogen bonds while having the least molecular weight to do so, allowing it to form large ice crystals with large gaps or voids within, to the point where any volume of ice has always less water than the same volume of liquid water. This is also the reason why completely filling up a water bottle and leaving it in the refrigerator will make the bottle burst, as the water turns to ice, becoming less dense, and expanding.
Every other known substance goes from more dense to least dense in the order you assumed (solid, liquid, gas, plasma). Water has all kinds of exceptions in chemistry due to having two hydrogen atoms whose electron clouds are shifted toward the much more electronegative oxygen atom. It also has neutral acidity and given enough time can dissolve pretty much anything because it behaves like a mass of strong dipoles, destabilising other chemical bonds with its chaotic magnetic moment.
