To find this you have to find the molar mass of CO2 which you can get on the periodic table, 12 + 16 + 16 = 44 g/mol
4.49 x 10^0 / 44 g/mol = .1020 mol CO2
1 mol = 6.022 x 10^23 molecules (avogadros number)
so .1020 mol x 6.022 x 10^23 =
6.14 x 10 ^22 molecules CO2
