91Ó°ÊÓ

The halogen elements include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Here are their melting points (MP) and boiling points (BP) in degrees Celsius: - Fluorine (F): MP = -219.67 °C, BP = -188.11 °C - Chlorine (Cl): MP = -101.5 °C, BP = -34.04 °C - Bromine (Br): MP = -7.2 °C, BP = 58.8 °C - Iodine (I): MP = 113.7 °C, BP = 184.3 °C - Astatine (At): MP and BP values have large uncertainties due to its high instability and short half-life. However, it can be assumed to be a solid at a room temperature.

Using the given melting and boiling points, we can determine the physical state of each halogen at room temperature (25 °C). - Fluorine (F): Since both MP and BP are below 25 °C, fluorine will be in the gaseous state at room temperature. - Chlorine (Cl): As its MP is less than room temperature, and BP is greater than room temperature, chlorine is also in the gaseous state at room temperature. - Bromine (Br): Bromine has a MP lower than room temperature and a BP higher than room temperature, therefore it is in the liquid state at room temperature. - Iodine (I): Iodine has both its MP and BP above room temperature, thus, iodine exists in the solid-state at room temperature. - Astatine (At): This element can be assumed as a solid at room temperature.

Based on the comparison of melting and boiling points with room temperature, the physical state of each halogen at room temperature is as follows: - Fluorine (F): Gas - Chlorine (Cl): Gas - Bromine (Br): Liquid - Iodine (I): Solid - Astatine (At): Solid