If you have 20.0 g of co2, how many atoms of oxygen (o) are present in the sample?

20 g of CO₂ have 5.47x10²³ oxygen atoms

Explanation:

1 mol of CO₂ has 1 mol of C and 2 moles of O.

Mass / Molar mass = Moles

20 g / 44 g/m = 0.454 moles

In 1 mol we find 2 moles of O

In 0.454 moles of CO₂, we will find ( 0.454  .2) = 0.909 moles

1 mol has 6.02x10²³ atoms

0.909 moles have (0.909 .  6.02x10²³) = 5.47x10²³ atoms