At a certain temperature and pressure, 0.20 mol of carbon dioxide has a volume of 3.1 L. A 3.1-L sample of hydrogen at the same temperature and pressure ____.
Answer: A 3.1 L sample of hydrogen at the same temperature and pressure contains the same number of molecules.
Explanation: As we know ;"1 mole of any gas at STP occupies exactly 22.4 L of volume". Therefore, CO₂ and H₂ gas having same number of moles (0.20 moles) will occupy exactly the same volume.