Question

How many moles are in  1.29 x 10²⁴ hydrogen atoms in HF?

Answer 1

1 mol contains $6.022 \times 10^{23}$ atoms.

Proportion:

1 mol – $6.022 \times 10^{23}$

x - $1.29 \times 10^{24}$

$x = \frac{1 \times 1.29 \times 10^{24}}{6.022 \times 10^{23}} \\ = 2.14 \;mol$

Answer: 2.14 mol