Given :
Number of He atoms, [tex]n = 3.4\times 10^{24}[/tex] atoms.
To Find :
How many grams are their in given number of He atoms.
Solution :
We know, molecular mass of He is 4 g. It means that their are [tex]6.022 \times 10^{23}[/tex] atoms in 4 g of He.
Let, number of gram He in [tex]3.4\times 10^{24}[/tex] atoms is x , so :
[tex]x = \dfrac{3.4\times 10^{24}}{6.022\times 10^{23}}\times 4\\\\x = $22.58\ g[/tex]
Therefore, grams of He atoms is 22.58 g .