The object that becomes solid when heated:

When an object becomes solid upon heating, it is due to a phenomenon called phase change. Phase change refers to the transformation of matter from one state to another, such as from a liquid to a solid or from a solid to a gas. There are various substances that undergo phase changes, but for the purpose of this response, let's focus on a specific example - water.

Water and its phase changes:

Water is a common substance that undergoes phase changes at specific temperatures. At normal room temperature (around 25 degrees Celsius), water exists in a liquid state. However, when it is heated to its boiling point, which is 100 degrees Celsius at sea level, it undergoes a phase change from a liquid to a gas, known as water vapor.

Conversely, when water is cooled below its freezing point, which is 0 degrees Celsius at sea level, it undergoes a phase change from a liquid to a solid, forming ice. This is the specific example we are looking for - an object that becomes solid when heated.

Key points:
- Water undergoes a phase change from a liquid to a solid when cooled below its freezing point.
- The freezing point of water is 0 degrees Celsius at sea level.
- When water freezes, it forms ice, which is a solid state of water.

Conclusion:

In conclusion, the object that becomes solid when heated is water. When water is cooled below its freezing point, it undergoes a phase change from a liquid to a solid, forming ice. This phenomenon is a common example of how substances can change their state when exposed to different temperatures.

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