# Question #f6570

##### 1 Answer

Simple,

Firstly, you want to find the number of moles in

So, as you probably already know

Number of Particles = Number of moles x Avogadro's constant

Since we re to find the number of moles

Number of moles = Number of Particles/Avogadro's Constant

1.26 moles in

Now, since we are to calculate the mass, we will use this formula

No. of moles =

The molar mass of helium is 4.00g/mol

Rearranging this equation to our needs, we have

Mass = Number of moles x Molar Mass

Mass =

Mass =

Thus, there is 5.04g of helium in

Hope this helps