You're asking about an element that would condense from a gaseous state to a liquid state at room temperature when cooled from 100 degrees Celsius.

Here's the breakdown:

* Room Temperature: This is typically considered to be around 20-25 degrees Celsius.

* Condensation: This occurs when a gas changes into a liquid.

The element that fits this description is bromine (Br). Here's why:

* Bromine at 100°C: Bromine is a reddish-brown liquid at room temperature. At 100°C, it would be in its gaseous state.

* Cooling to Room Temperature: When you cool bromine gas down to room temperature, it will condense into its liquid form.

Important Note: While other elements like chlorine (Cl) and iodine (I) are also halogens, they are gases at room temperature. They would need to be cooled to even lower temperatures than room temperature to condense.