Which gas is commonly used to fill balloons?

Which gas is commonly used to fill balloons?

• A. Argon
• B. Neon
• C. Hydrogen
• D. Helium

Answer: (D)

Lift in balloons comes from using a gas that is lighter than the surrounding air. Helium fits this requirement with a very low density, so balloons filled with it rise. It’s also inert, meaning it won’t react with other materials or catch fire, which makes it safe for general use. Hydrogen could also provide lift, but it is highly flammable, posing a serious fire risk around people and flames, so it’s not used for standard balloons. Argon is heavier than air, so it wouldn’t lift a balloon, and neon, while light, is expensive and impractical for routine use. That combination of buoyancy, safety, and practicality makes helium the common choice.

Lift in balloons comes from using a gas that is lighter than the surrounding air. Helium fits this requirement with a very low density, so balloons filled with it rise. It’s also inert, meaning it won’t react with other materials or catch fire, which makes it safe for general use.

Hydrogen could also provide lift, but it is highly flammable, posing a serious fire risk around people and flames, so it’s not used for standard balloons. Argon is heavier than air, so it wouldn’t lift a balloon, and neon, while light, is expensive and impractical for routine use. That combination of buoyancy, safety, and practicality makes helium the common choice.