How many hydrogen atoms are in 5.20 mol of ammonium sulfide?

1) Molecular formula of ammonium sulfide

(NH4) 2 S

2) That means that there are 2*4 = 8 atoms of hydrogen in each molecule of ammoium sulfide, so in 5.20 mol of molecules will be 8 * 5.20 mol = 41.6 moles of atoms of hydrogen

3) To pass to number of atoms multiply by Avogadro's number: 6.022 * 10^23

41.6 moles * 6.022 * 10^23 atoms / mol = 250.5 * 10^23 = 2.50 * 10^25 atoms

Answer: 2.50 * 10^25