Helium
Yes, hydrogen gas is lighter than air and can make balloons float. However, hydrogen is highly flammable and can be dangerous, so it is not commonly used today. Helium is a safer alternative for making balloons float.
Nitrous oxide does not make balloons float. Helium gas is typically used to make balloons float due to its low density compared to air. Nitrous oxide is commonly used as a propellant in whipped cream dispensers and in medical settings for its anesthetic properties.
Helium gas is most commonly used to fill balloons to make them float. Helium is lighter than air, which causes the balloon to rise and float.
Usually helium unless you're blowing it up yourself, then it's carbon dioxide.
If I am right in interpreting the question as "Are balloons normally filled with hydrogen and oxygen?", then the answer would be no. Although they can be, as both substances are gases, the majority of balloon are filled with air, a mixture of nitrogen, oxygen, carbon dioxide and other gases. If you mean the balloons that float, they are filled with helium
So that the balloons float
Balloons float in the air because they are filled with a gas that is lighter than the surrounding air. This gas, typically helium or hydrogen, creates buoyancy, causing the balloon to rise and float.
Balloons filled with it float in air
Those balloons are filled with helium gas. Helium is lighter than air. Helium is a noble gas.
Helium
Because it is a safe gas that is less dense than air, thus balloons float in air
Balloons float in the air because they are filled with a gas that is lighter than the surrounding air, such as helium or hot air. This creates a buoyant force that allows the balloon to rise and float.
Balloons filled with helium float because helium is lighter than the surrounding air, creating a lifting force. This is known as buoyancy. Regular air-filled balloons are denser than the surrounding air and do not float.
Helium gas is lighter than air and hence balloons filled with helium will float in air.
Helium is lighter than air, hence balloons filled with helium will float and rise up.
The balloons that float usually contain helium in them, which is lighter than air. This enables the balloon to float.
Balloons can be filled with air (don't float), or with hydrogen or helium (float because the gas is less dense). Hot air balloons use burners to heat the air so that it becomes slightly less dense than the cooler air around it, providing some lift.