States of Matter

Hydrogen bonds contribute to water's unique properties, including its density anomaly when frozen, its high heat capacity, and its ability to act as a solvent.

Unlike most substances, water expands when it freezes because its molecules form a crystalline hexagonal structure held together by hydrogen bonds. This structure takes up more space than liquid water, making ice less dense.

About 68.7% of the Earth's freshwater is locked up in glaciers, ice caps, and permanent snow (often referred to collectively as icebergs or ice sheets). Only a very small fraction of freshwater is available in liquid form on the surface in rivers and lakes.

Blood plasma, which makes up about 55% of blood volume, is roughly 90-92% water. When considering whole blood (including red blood cells, white blood cells, and platelets), water constitutes about 80% of the total composition.

The human brain is composed of approximately 73% to 80% water. Among the given options, 75% is the most accurate representation of this composition.

The human body is made up of approximately 60% to 70% water depending on age, gender, and hydration levels. Among the choices, 70% is the closest standard estimate.

Water has the chemical formula H2O, which means it consists of two hydrogen atoms bonded to one oxygen atom. Therefore, it is made up of oxygen and hydrogen.

Heat (thermal energy) always transfers spontaneously from a warmer object to a cooler object. In this scenario, energy from the warmer room-temperature water transfers to the colder ice cubes, causing the ice to absorb heat and melt.

Boiling point is an intensive physical property, meaning it is characteristic of the substance itself and does not change regardless of the sample size. Mass and volume are extensive properties that change with the amount of liquid, and color alone is not a definitive identifier.

Solids have a fixed shape and a fixed volume because their particles are tightly packed and held in place. Liquids have a fixed volume but can change shape to match their container because their particles can flow past one another.

Condensation is the process where water vapor (a gas) cools down and changes into liquid water. This is the opposite of evaporation, where liquid water turns into gas. Other options like radiation and convection are methods of heat transfer, not phase changes.

Ice floats on liquid water because it is less dense than the liquid form. When water freezes, its molecules form a crystalline structure that spaces them further apart, increasing the volume and lowering the density.

Ice is the solid state of water, which exists at or below 0 degrees Celsius. For ice to begin melting into liquid water, the temperature must rise above this freezing point.

Condensation is the process where a gas cools down and changes into a liquid. During this phase change, the particles lose thermal energy, slow down, and move closer together.

When you exhale, warm and moist air from your lungs meets the cold outside air. The water vapor in your breath rapidly cools and condenses into tiny liquid water droplets, which appear as a visible mist.