Question

Calculate the number of moles for the following:
i) 52 g of He
ii) number of He atom

Answer 1

Given mass $=52g$

Molecular mass of He $=4g$

$\left(i\right)$ No. of moles $=\frac{Givenmass}{Molecularmass}=\frac{52}{4}=13$ moles

$\left(ii\right)$ No. of atoms $=$ No. of moles of $He$ atom $\times$ Avogadro's no. $=13\times 6.022\times {10}^{23}=783\times {10}^{24}$ atoms