Helium gas is used in gas balloons instead of hydrogen gas because it is

The correct answer is Non-combustible.

• Hydrogen and helium are the most commonly used lift gases.
• Although helium is twice as heavy as (diatomic) hydrogen, they are both so much lighter than air that this difference is inconsequential.
• Helium is the second lightest gas. For that reason, it is an attractive gas for lifting as well.
  • A major advantage is that this gas is Non-combustible.
  • Today helium is used instead of hydrogen since it is inert so non-flammable which makes things a lot safer. Hydrogen can ignite very easily when mixed with the oxygen of the surrounding air.

Key Points

• Hydrogen:
  • Hydrogen gas consists of Hydrogen molecules.
  • The molecule consists of two atoms.
  • The atom has only one electron.
  • The nucleus of the hydrogen atom consists of only one proton.
• Helium:
  • Helium is the second lightest atom.
  • One nucleus of a Helium atom consists of two protons and two neutrons.
  • Helium atoms do not combine into molecules.
  • That is why it is called an inert gas, which consists of free atoms.