Final answer:
Water shrinks when heated below 4 °C due to its unique behavior as it cools and freezes into ice.
Step-by-step explanation:
Water shrinks when heated below 4 °C. This is because water contracts as it cools down to its freezing point at 0 °C, and then expands as it freezes into ice. As a result, the temperature at which water starts shrinking when heated is below 4 °C.
For example, if water at 1 °C is heated, it will shrink instead of expanding. However, this shrinkage is very small and not easily noticeable.