• # question_answer 41) Calculate the number of atoms present in: (i) 52 moles of He (ii) 52 amu He (iii) 52 g He (Atomic mass of Helium is 4 amu).

(i) Number of atoms s= Number of moles $\times 6.023\times {{10}^{23}}$ $=52\times 6.023\times {{10}^{23}}$ $=3.13\times {{10}^{25}}$ (ii) 4 amu He has one atom. $\therefore$ 52 amu He will have 13 atoms. (iii) Number of atoms $=\frac{\text{mass}}{\text{Atomic}\,\text{mass}}\times 6.023\times {{10}^{23}}$ $=\frac{52}{4}\times 6.023\times {{10}^{23}}$ $=7.83\times {{10}^{24}}$