How many atoms is 50 g of He?
Atomic mass He = 4.002 u.m.a4.002 g --------------- 6.02x10²³ atoms50 g ------------------ ? atoms50 x ( 6.02x10²³) / 4.002= 3.01x10²⁵ / 4.002= 7.52x10²⁴ atoms of He
