Answer: Hydrogen, because it has lower molar mass.
- A Oxygen, because it is heavier according to most researchers
- B Hydrogen, because it has lower molar mass
- C Both diffuse at the same rate in the majority of cases studied
- D Neither gas diffuses as widely reported
Correct answer: B. Hydrogen, because it has lower molar mass
Explanation: By Graham Law, lighter gases diffuse faster, and hydrogen has a much lower molar mass than oxygen.
Boyle's law: at constant temperature the pressure of a fixed mass of gas is inversely proportional to its volume (P ∝ 1/V), so the P–V plot is a hyperbola — halving the volume doubles the pressure. Image: Reginaprice2013, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Discover why gases expand to fill any container while liquids flow and solids hold their shape. Master the gas laws, the ideal gas equation, and the reasons real gases deviate from ideal behavior.