Question

what happens to the chemical formula and structure of water when it changes states of matter? water molecules break apart to form individual gas atoms. water molecules harden into a new compound of ice molecules. water molecules melt into a new compound of gas molecules. nothing happens to the chemical formula and structure.

Explanation:

• When water changes states (solid, liquid, gas), it's a physical change. Physical changes don't alter the chemical formula or the structure of the molecules (water is always \(H_2O\) at the molecular level, and the water molecules themselves remain intact, only the intermolecular forces and spacing change).
• The first option is wrong because water molecules don't break into atoms during state changes (that's a chemical reaction, like electrolysis).
• The second option is wrong because ice is still \(H_2O\), not a new compound.
• The third option is wrong because gas (water vapor) is still \(H_2O\) molecules, not a new compound, and "melt" is for solid to liquid, not liquid to gas.
• The fourth option is correct as state changes are physical and don't change the chemical formula or molecular structure.

Answer:

D. Nothing happens to the chemical formula and structure.