Which term describes a gas that is stored under pressure?

• A. Gas which is stored under pressure.
• B. A liquid fuel stored in a pressurized vessel.
• C. A solid material used for cushioning.
• D. A chemical that rapidly expands when heated.

Answer: (C)

A gas stored under pressure is called a compressed gas. This means the gas is kept in a container at a pressure higher than the surrounding atmosphere, typically in sturdy cylinders designed to safely hold the high pressure. This concept contrasts with a liquid fuel in a pressurized vessel (which is a liquid, not a gas), a solid material used for cushioning (a solid, not a gas), or a chemical that rapidly expands when heated (which describes a substance with explosive or vigorous expansion behavior, not simply a gas stored under pressure). The key idea is the gas is kept at elevated pressure inside a container, hence “compressed gas.”