Which of the following correctly describes the physical state of each halogen at room temperature (approximately 25°C)?

• A. Fluorine and bromine are liquids, chlorine and iodine are solids.
• B. All halogens are gases at room temperature.
• C. Fluorine is a solid, chlorine and bromine are liquids, and iodine is a gas.
• D. Fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid.

Answer: (D)

Verified step by step guidance

1. Recall that halogens are elements in Group 17 of the periodic table, including fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Their physical states at room temperature vary due to differences in intermolecular forces and molecular masses.
2. Understand that the physical state of a substance at room temperature depends on the strength of intermolecular forces: stronger forces generally lead to solids or liquids, while weaker forces result in gases.
3. Identify the physical states of each halogen at approximately 25°C based on their molecular properties: fluorine (F2) and chlorine (Cl2) are gases because they have relatively weak van der Waals forces; bromine (Br2) is a liquid due to stronger intermolecular forces; iodine (I2) is a solid because it has even stronger intermolecular forces.
4. Compare the given options with the known physical states: the correct description is that fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid at room temperature.
5. Conclude that the correct answer matches the known physical states of the halogens at room temperature, confirming the statement: 'Fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid.'