At room temperature, propane is in what state?

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

Answer: (B)

Propane is a gas at room temperature because its boiling point is far below typical room temperatures. Propane boils at about -42°C at 1 atmosphere of pressure, so once the temperature is around 20°C, propane exists as a gas. In a pressurized tank, some propane can be liquid due to the pressure, but under normal room conditions it is the gaseous form. The other states don’t apply here: solids would require much colder temperatures, liquids would occur only if the temperature were between the melting and boiling points (which isn’t the case since the boiling point is well below room temperature), and plasma is an ionized state that requires much higher energy.