John Dalton
Although the concept of the atom dates back to the ideas of Democritus, the English meteorologist and chemist John Dalton formulated the first modern description of it as the fundamental building block of chemical structures.
Here, as they both are physical things without any magnetic property & density difference, screening would be best.
In short, Your Answer would be Option C
Hope this helps!
Atomic mass of helium is 4.002642g/mol
(542000g)/(4.002642g/mol)*6.02*10^23 = 8.15*10^28 atoms
Evaporation and transpiration
