There are four Hydrogen atoms in one molecule of Methane (CH₄).
And there are 6.022×10²³ molecules in 1 mole of CH₄.
So,
Number of Hydrogen atoms is 1 mole of CH₄ are,
 = 6.022 × 10²³ × 4
 
 = 2.4 ×10²⁴ Hydrogen Atoms
Now calculating for 2 moles,
As, 
 1 mole of CH₄ contains = 2.4 ×10²⁴ Hydrogen Atom
Then,
 2 moles of CH₄ will contain = X Hydrogen Atoms
Solving for X,
 X = (2 moles × 2.4 ×10²⁴ Hydrogen Atom) ÷ 1 mole
 X = 4.8 × 10²⁴ Hydrogen Atoms