Answer: Sodium/Na
Explanation: Molar mass is basically a measure of how heavy 6.02 x 10^23 atoms of a substance is, measured in grams.
So, if Sodium has the lowest molar mass then that means it’s molecules are very light. I’ll give a comparison: if you have 10 kilograms of bricks and 10 kilograms of feathers, will you have more feathers or bricks? Feathers, of course.
Mathematically it looks like this
50g/22.99g/mol = 2.17 mol
2.17 mol • 6.02 x 10^23 = 1.31 x 10^24 atoms
50g/58.93g/mol = 0.85 mol
You can see that as molar mass increases that the number of moles, and consequently, atoms, decreases.
Hope this helped
