Question

Calculate the number of atoms in each of the following:
(i) 52 moles of Ar
(ii) 52 u of He
(iii) 52 g of He

Answer 1

(i) The number of atoms present in 52 mol of Ar are $52\times 6.023\times {10}^{23}=3.13\times {10}^{25}$ atoms.

(ii) 52 u of He will contain $\frac{52}{4}=13$ atoms (as atomic mass of He is 4 amu).

(iii) 52 g of He will contain $\frac{52}{4}\times 6.023\times {10}^{23}=7.82\times {10}^{24}$ atoms.