Answer is: 5. 3.05 moles of NH3.
a) n(H₂O) = 3,05 mol. In one molecule of water, there are three atoms (two hydrogen and ond one oxygen):
N(atoms) = 3 · 3,05 mol · 6,022·10²³ 1/mol = 55,1·10²³.
b) n(Kr) = 3,05 mol. N(Kr) = 3,05 mol · 6,022·10²³ 1/mol = 18,37·10²³.
c) (Ne) = 3,05 mol. N(Ne) = 3,05 mol · 6,022·10²³ 1/mol = 18,37·10²³.
d) n(NH₃) = 3,05 mol. In one molecule of ammonia there are four atoms.
N(atoms) = 4 · 3,05 mol · 6,022·10²³ 1/mol = 73,46·10²³.