4 ms·The given value for hydrogen is for hydrogen gas (i.e. H₂), while helium is just a single atom.by Denvercoder9 6y agoThe given value for hydrogen is for hydrogen gas (i.e. H₂), while helium is just a single atom.tyingq 6y agoThat's what you would expect, though. Helium gas is "He1", hydrogen gas is "H2".meepmorp 6y agoI think that was their point: hydrogen gas is diatomic, so it makes intuitive sense for it to be larger than helium