Multiple choice

Which of the following is the lightest gas?

  1. Hydrogen

  2. Oxygen

  3. Nitrogen

  4. Carbon dioxide

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hydrogen is the lightest gas with the lowest atomic mass (1 amu) among all gases. It is the first element in the periodic table and forms H2 molecules in its gaseous state.