1. Helium: Helium is the most common gas used in balloons because it is non-flammable and lighter than air. This makes balloons filled with helium float.
2. Hydrogen: Hydrogen is also lighter than air and can be used to fill balloons, but it is highly flammable and can pose safety risks. Therefore, hydrogen is typically used only for scientific or research purposes, not for recreational balloons.
3. Air: Balloons can also be filled with regular air, but they will not float as well as balloons filled with helium or hydrogen. Air-filled balloons are commonly used for decorations or promotional purposes.
4. Other gases: In some cases, balloons might be filled with other gases such as nitrogen or argon. These gases are generally safe and non-flammable, but they are denser than helium or hydrogen, so they will cause the balloons to float lower.
The choice of gas to fill a balloon depends on the desired application, safety considerations, and buoyancy requirements.
