Molar mass CO₂ = 44.0 g/mol
44.0 g ----------------- 6.02x10²³ molecules
74.5 g ----------------- ??
74.5 x ( 6.02x10²³) / 44.0
= 1.019x10²⁴ molecules of CO2
Calculate the number of atoms :
CO₂ => 1 atom of Carbon , 2 atoms of Oxygen ( 1 + 2 = 3 atoms )
therefore:
1 molecule CO2 ---------------------- 3 atoms
1.019x10²⁴ CO2 --------------------- ?? atoms
3 x ( 1.019x10²⁴) / 1 =
= 3.057x10²⁴ atoms of CO₂
hope this helps!