How many hydrogen atoms are in 4.00 mol of ammonium sulfide?

(NH4)2S

there are 8 hydrogen atoms for every molecule ofammoniumsulfide

NA = 4 mol x 6.02 x 10^23 = 2.4 x 10^24 molecules of ammonium sulfide

number of hydrogen atoms = 8 x

2.4 x 10^24 = 2.93 x 10^25 ( 3 sig. figure)