Answer: There are
number of H atoms in 7.80 mol of ammonium sulfide.
Explanation:
The formula of ammonium sulfide is
.
There are 2 nitrogen atoms, 8 hydrogen atoms and 1 sulfur atom in one molecule of ammonium sulfide.
Calculate moles of hydrogen atoms as follows.
= 62.4
According to Avogadro's number 1 mole contains 
Therefore, calculate number of H atoms as follows.

= 
= 
Thus, there are
number of H atoms in 7.80 mol of ammonium sulfide.