Question

What is the mass, in grams, of a sample of 6.98 × 1024 atoms of magnesium (Mg)?

Answer 1

N=6.98*10²⁴
Nₐ=6.022*10²³ mol⁻¹

n(Mg)=N/Nₐ

m(Mg)=n(Mg)M(Mg)=M(Mg)N/Nₐ

m(Mg)=24.3g/mol*6.98*10²⁴/(6.022*10²³mol⁻¹)=281.7 g