Earth Science And Environmental Pollution Practice Exam

Water’s polarity is what governs many of its distinctive behaviors, so the statement that it is nonpolar is not true. The oxygen atom in a water molecule is more electronegative than hydrogen, pulling electron density toward itself in the O–H bonds. Because the molecule is bent rather than straight, those partial charges don’t cancel out, giving water a net dipole moment. That polarity enables hydrogen bonding between water molecules, which is the glue that holds the liquid together strongly and leads to high surface tension—myd cohesive forces at the surface pull inward, creating a tight “skin.” It also explains why ice expands upon freezing: the hydrogen-bonded network in solid water forms an open, hexagonal structure that is less dense than liquid water, so ice floats. So the true description is that water is polar and forms strong hydrogen bonds, which accounts for its high surface tension and the expansion upon freezing; the nonpolar description does not fit.