Question

Which from following elements of halogen family is in liquid state at room temperature?

• A. Iodine
• B. Astatine
• C. Bromine
• D. Fluorine

Hint:

There are only two liquid elements at standard room temperature in the entire periodic table: Mercury (Hg), which is a metallic conductor, and Bromine ($\text{Br}_2$), which is a non-metallic halogen!

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks to identify the unique halogen element (Group 17) that exists naturally as a liquid state at standard room temperature conditions.

Step 2: Detailed Explanation: Down Group 17 of the periodic table, the physical state of the halogens changes systematically from gas to liquid to solid due to a steady increase in atomic size and molecular mass. This increases the strength of the intermolecular London dispersion forces:

• Fluorine ($\text{F}_2$) and Chlorine ($\text{Cl}_2$): Small molecules with weak dispersion forces, existing as gases at room temperature.

• Bromine ($\text{Br}_2$): Possesses intermediate dispersion forces strong enough to hold the molecules together as a dense, volatile reddish-brown liquid at room temperature.

• Iodine ($\text{I}_2$) and Astatine (At): Large atoms with strong dispersion forces that form solid crystalline networks at room temperature.
Thus, Bromine is the only non-metallic element in the periodic table that is liquid at room temperature.

Step 3: Final Answer: The halogen element that exists in a liquid state at room temperature is Bromine, matching option (C).