Which property of water changes as it transitions from solid (ice) to liquid to gas (vapor)?

• A. The number of hydrogen atoms in each molecule
• B. The atomic number of oxygen in water
• C. The chemical composition of water molecules
• D. The arrangement and movement of water molecules

Answer: (D)

Verified step by step guidance

1. Understand that the chemical composition of water (H\_2O) remains constant during phase changes; each molecule always contains 2 hydrogen atoms and 1 oxygen atom.
2. Recognize that the atomic number of oxygen is a fixed property of the element and does not change regardless of the state of water.
3. Focus on the physical changes occurring during phase transitions: from solid (ice) to liquid (water) to gas (vapor), the arrangement and movement of water molecules change significantly.
4. In ice, water molecules are arranged in a rigid, ordered lattice with limited movement; in liquid water, molecules are close but can move past each other; in vapor, molecules are far apart and move freely.
5. Conclude that the property that changes during these phase transitions is the arrangement and movement of water molecules, not their chemical composition or atomic structure.