State of bromine at room temperature?

• A. Liquid
• B. Gas
• C. Solid
• D. Plasma

Answer: (A)

Whether a substance is a solid, liquid, or gas at room temperature depends on where room temperature sits relative to its melting and boiling points. Bromine is a diatomic molecule (Br2) with a melting point of about −7 °C and a boiling point of about 59 °C. At room temperature (around 20–25 °C), it has already melted but has not boiled, so it exists as a liquid. The relatively high boiling point for a nonmetal comes from the large, highly polarizable Br2 molecules, which experience stronger van der Waals forces and stay liquid until warmer temperatures. It’s not a solid because room temperature is above its melting point, and it’s not a gas because it’s below its boiling point. Therefore, bromine is a liquid at room temperature.