Final answer:
The amount of matter stays the same when water changes state, following the law of conservation of mass, which applies to atoms and mass during physical changes, including changes from ice to liquid water to water vapor. Hence, option (c) is correct.
Step-by-step explanation:
When water changes state, the amount of matter stays the same. This principle falls under the law of conservation of mass, which states that the total mass, the number of atoms, and the number of molecules remain constant during a physical change.
Whether water is in its solid state (ice), liquid state (water), or gaseous state (water vapor), the actual quantity of matter does not change despite differences in volume, density, or energy content.
For example, when ice melts to become water, the solid structure breaks down, but the total amount of water - the mass and the number of molecules - is conserved. Similarly, when water boils and turns into steam, it expands enormously, but again, there is no loss or gain in the amount of matter. This transition between states is a physical, rather than a chemical, change and does not alter the matter's mass, just its physical form and density.