Hey there!
First convert atoms to moles.
There are 6.022 x 10²³ atoms in a mole.
We have 4.23 x 10²⁴ atoms.
(4.23 x 10²⁴) ÷ (6.022 x 10²³) = 7.024 moles
The molar mass of helium is 4.00 grams.
4.00 x 7.024 = 28.1
There are 28.1 grams in 4.23 x 10²⁴ atoms of He.
Hope this helps!
