How many moles are in 1.2 x 10^24 atoms of Y

We know that, 1 mole of any substance contain 6.022 X 10^23 atoms/molecules. Thus, 2.14 moles are present in 1.29x10^24 hydrogen atoms in HF.

Explanation:

divide it by avogadro's constant

that is 6.02 × 10²³

1.2 × 10²⁴ / 6.02 × 10²³

= 2 mol

the dissolution of polymer can be thermodynamically described in 2 steps.