a) nr. moli = masa / masa moleculara sau atomica (in cazul atomilor)
=> 1 mol atomi de C cantaresc 12 g
b) orice mol dintr-un element contin 6,022x10la23 atomi
=> 1 mol C are 6,022x10la23 at. C
c)
daca 12 g .......... corespund 6,022x10la23 atomi
a g ........................................1
=> a = 12/6,022x10la23 = 2x10la-23 g