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.

Calculate the number of atoms in each of the following (i) 52 moles of

1.	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» Solution :(i) 1 mole of Ar = `6.022 xx 10^(23)` atoms `therefore 52` moles of Ar `=52 xx 6.022 xx 10^(23) = 3.131 xx 10^(25)` atoms of Ar. (ii) 4U of He = 1 atom of He. `therefore 52 u` of He `=52/4 = 13` atoms of He (III) 1 mole of He, i.e., 4 g of He contain `6.022 xx 10^(23)` atoms `therefore` No. of He atoms in 52 g of `He = (6.022 xx 10^(23))/4xx 52 = 7.8286 xx 10^(24)`