For Neon (Ne), the atomic mass is 10 daltons, so the molar mass is 10
grams. This means that one mole (Avogadro's number of particles, 6.02
x 10^23) has a mass of 10 grams. Hydrogen, with an atomic mass of
1 dalton for it's single proton, the molar mass would be 1 gram. With
Neon, the speed of the individual Neon atoms is
proportional to 1 / sqrt(10). So it is helium.