Which elements exist as liquids at standard temperature and pressure?

Which elements exist as liquids at standard temperature and pressure?

• A. Bromine and Mercury
• B. Oxygen and Nitrogen
• C. Hydrogen and Helium
• D. Sodium and Chlorine

Answer: (A)

At standard temperature and pressure, an element will be a liquid if its melting point is below that temperature and its boiling point is above it, so it sits between solid and gaseous phases. Bromine has a melting point around -7°C and a boiling point around 59°C, placing it as a liquid at room temperature. Mercury melts at about -39°C and boils at about 357°C, so it is also liquid at room temperature. The other elements listed are either gases at STP (oxygen, nitrogen, hydrogen, helium, chlorine) or a solid (sodium), so they do not exist as liquids under those conditions.

At standard temperature and pressure, an element will be a liquid if its melting point is below that temperature and its boiling point is above it, so it sits between solid and gaseous phases. Bromine has a melting point around -7°C and a boiling point around 59°C, placing it as a liquid at room temperature. Mercury melts at about -39°C and boils at about 357°C, so it is also liquid at room temperature. The other elements listed are either gases at STP (oxygen, nitrogen, hydrogen, helium, chlorine) or a solid (sodium), so they do not exist as liquids under those conditions.