The water anomaly

Excellent. Your answer is correct!
If the water in the cup is freezing, its mass will not change because neither further water has been added nor has some of it disappeared. The volume of the ice has increased in contrast to the liquid water because it no longer fits into the cup.

image

The density is the ratio between the mass of a body or a substance and its volume.

density = mass : volume

For the volume has increased during the freezing process the term is diveded by a larger number –the result (and thus the density) is smaller in contrast to liquid water.

While other substances shrink during cooling and freezing, water reacts differently. Water expands while cooling from 4°C to 0°C (freezing point of the water). This phenomenon is called the "anomaly of the water".

If you placed the cup in the plain sun now, so that the ice was melting, would the water start overflowing?

schliessen