Calculate the number of atoms in 52 g of Helium (He)

Explanation

Mass of 1 mole of He = 4.0
Number of moles of He `("mass of He ")/("mass of 1mole of He ")`
`= (52g)/(4.0 g"mol"^(-1)) = 13` mol
Number of atoms of He
= Number of moles ` xx 6.022 xx 10^23`
= 13 mol` xx 6.022 xx 10^23` atoms/mol
` = 78.286 xx 10^23` atoms of He