Question

How many atoms is 50 g of He?

Answer 1

Atomic mass He = 4.002 u.m.a

4.002 g --------------- 6.02x10²³ atoms
50 g ------------------ ? atoms

50 x ( 6.02x10²³) / 4.002

= 3.01x10²⁵ / 4.002

= 7.52x10²⁴ atoms of He