Chemistry - Mole Concept Question with Solution | TestHub

(i)  1 mol of Ar = 6.022 x 10²³atoms.

52 moles of Ar = 52 x 6.022 x 10²³atoms

= 313.144 x 10²³atoms

= 3.131 x 10²⁵atoms

(ii)  4 u of He = 1 He atom

$\therefore$52 u of He$=\frac{52}{4}$He atoms = 13 He atoms.

(iii)  1 mol atom of He = 4 g = 6.022 x 10²³atoms.

52 g of$\text{He}=\frac{52\times 6\text{.}022\times 10^{23}}{4}\text{atoms}$

= 78.286 x 10²³atoms

= 7.8286 x 10²⁴atoms.